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使用泛型实现一个方法返回不同的类型<T,V>

 
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/**

         * 实现的效果是:

         * 同一个service.getProvider()方法

         * 

         * Provider 使用request1参数来调用,得到的返回值是Provider

         * Provider2使用request2参数来调用,得到的返回值是Provider2

         */

package a;

import java.util.List;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElementWrapper;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlTransient;
import javax.xml.bind.annotation.XmlType;

/**
 * 
 * @author bragel
 *
 */
@XmlType
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "provider")
public class Provider {
    
    @XmlElement(name = "provider_id")
    private int id;

    private Address address;

    /**
     * List会转化成一个item数组,item节点是network,包含items的节点是networks
     */
    @XmlElementWrapper(name = "networks")
    @XmlElement(name = "network")
    private List<Network> networks;
  
    @XmlElement(name = "is_primary_care_physician")
    private boolean primaryCarePhysician;

    /**
     * 不会被输出
     */
    @XmlTransient
    private String remark;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public List<Network> getNetworks() {
        return networks;
    }

    public void setNetworks(List<Network> networks) {
        this.networks = networks;
    }

    public boolean isPrimaryCarePhysician() {
        return primaryCarePhysician;
    }

    public void setPrimaryCarePhysician(boolean primaryCarePhysician) {
        this.primaryCarePhysician = primaryCarePhysician;
    }

    public String getRemark() {
        return remark;
    }

    public void setRemark(String remark) {
        this.remark = remark;
    }
    
    
    public String toString() {
        return String.format("Provider:id:%s;address:%s;", id, address);
    }
    

}

 

package a;

import java.util.List;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElementWrapper;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlTransient;
import javax.xml.bind.annotation.XmlType;

/**
 * 
 * @author bragel
 *
 */
@XmlType
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "provider")
public class Provider2 {

    @XmlElement(name = "provider_id")
    private int id;

    @XmlElement(name = "address")
    private Address2 address2 = new Address2();

    /**
     * List会转化成一个item数组,item节点是network,包含items的节点是networks
     */
    @XmlElementWrapper(name = "networks")
    @XmlElement(name = "network")
    private List<Network> networks;
  
    @XmlElement(name = "is_primary_care_physician")
    private boolean primaryCarePhysician;

    /**
     * 不会被输出
     */
    @XmlTransient
    private String remark;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Address2 getAddress2() {
        return address2;
    }

    public void setAddress2(Address2 address2) {
        this.address2 = address2;
    }

    public List<Network> getNetworks() {
        return networks;
    }

    public void setNetworks(List<Network> networks) {
        this.networks = networks;
    }

    public boolean isPrimaryCarePhysician() {
        return primaryCarePhysician;
    }

    public void setPrimaryCarePhysician(boolean primaryCarePhysician) {
        this.primaryCarePhysician = primaryCarePhysician;
    }

    public String getRemark() {
        return remark;
    }

    public void setRemark(String remark) {
        this.remark = remark;
    }
    
    public String toString() {
        return String.format("Provider2:id:%s;address:%s;", id, address2);
    }
    

}

 

package a;

public class Request1 {
    private int providerId;
    private Integer networkId;
    private double latitude;
    private double longitude;

    @Override
    public String toString() {
        return String.format("ProviderIdentifier{providerId=%d, networkId=%d, latitude=%s, longitude=%s}", providerId, networkId, latitude, longitude);
    }

    public Integer getNetworkId() {
        return networkId;
    }

    public void setNetworkId(Integer networkId) {
        this.networkId = networkId;
    }

    public double getLatitude() {
        return latitude;
    }

    public void setLatitude(double latitude) {
        this.latitude = latitude;
    }

    public double getLongitude() {
        return longitude;
    }

    public void setLongitude(double longitude) {
        this.longitude = longitude;
    }

    public int getProviderId() {
        return providerId;
    }

    public void setProviderId(int providerId) {
        this.providerId = providerId;
    }
}

 

package a;

/*
 * @author Brage
 */
public class Request2 {
    private int providerId;
    private int addressId;


    @Override
    public String toString() {
        return String.format("ProviderIdentifier{providerId=%d, addressId=%d}", providerId, addressId);
    }


    public int getProviderId() {
        return providerId;
    }


    public void setProviderId(int providerId) {
        this.providerId = providerId;
    }


    public int getAddressId() {
        return addressId;
    }


    public void setAddressId(int addressId) {
        this.addressId = addressId;
    }


    

}

 

package a;


/**
 * 
 * @author bragel
 *
 */
public class RequestCommon {

    
    private int providerId;
    private Integer networkId;
    private double latitude = 0d;
    private double longitude = 0d;
    
    private int returnAddressId = 1;
    private int addressId = 0;

    public int getProviderId() {
        return providerId;
    }

    public void setProviderId(int providerId) {
        this.providerId = providerId;
    }

    public Integer getNetworkId() {
        return networkId;
    }

    public void setNetworkId(Integer networkId) {
        this.networkId = networkId;
    }

    public double getLatitude() {
        return latitude;
    }

    public void setLatitude(double latitude) {
        this.latitude = latitude;
    }

    public double getLongitude() {
        return longitude;
    }

    public void setLongitude(double longitude) {
        this.longitude = longitude;
    }

    public int getAddressId() {
        return addressId;
    }

    public void setAddressId(int addressId) {
        this.addressId = addressId;
    }

    public int getReturnAddressId() {
        return returnAddressId;
    }

    public void setReturnAddressId(int returnAddressId) {
        this.returnAddressId = returnAddressId;
    }

    
    
    
}

 

 

 

Provider与Provider2的属性大部分是相同的,只是address不同,Provider的address里带经纬度,而Provider2里的address2没经纬度,address2的属性是address的属性的子集。

 

Request1里包含经纬度来查询Provider,

Request2里包含addressId来查询Provider2,

RequestCommon是Request1和Request2属性的全集。

 

 

我们先来看主要类,其他Address, Address2, Network等之后再贴出。

 

package a;

import java.util.Arrays;

/**
 * 
 * @author bragel
 * 
 */
public class ProviderService {

    /**
     * 所有要使用到的泛型都必須在public/private等之後,返回類型void/String等之前用<>定義
     * 如<T, V>
     * 只是類型定義,不是返回類型,返回類型該是String或者T還是不能少
     * 
     * @param clientId
     * @param request
     * @param t
     * @return
     * @throws Exception
     */
    public <T, V> T getProvider(String clientId, V request, Class<T> t) throws Exception {

        /**
         * 1.request1, request2 -> RequestCommon(全集)
         */
        RequestCommon common = V2Util.convert(request);
        
        /**
         * 2.用RequestCommon查询数据库,获得Provider(全集)
         */
        Provider p = getProvider(common);

        /**
         * 3.Provider -> Provider2或者Provider?
         */
        return V2Util.convert(p, t, common.getReturnAddressId());
    }

    /**
     * 查询Provider
     * 
     * @param request
     * @return
     */
    private Provider getProvider(RequestCommon request) {
        Provider provider = new Provider();
        provider.setId(1);
        provider.setPrimaryCarePhysician(true);
        provider.setRemark("hello");

        Network n1 = new Network();
        n1.setId(1);
        n1.setCarrierGroupId(1);
        n1.setCarrierIds(Arrays.asList(new Integer[] { 1, 2 }));

        Network n2 = new Network();
        n1.setId(2);
        n1.setCarrierGroupId(1);
        n1.setCarrierIds(Arrays.asList(new Integer[] { 1, 2, 3 }));

        provider.setNetworks(Arrays.asList(new Network[] { n1, n2 }));

        /**
         * 根据这个returnAddressId,区分查询数据库
         */
        if (request.getReturnAddressId() == 1) {
            provider.setRemark("world");
        }

        Address address = new Address();
        address.setId(1);
        address.setCity("city");
        address.setCounty("country");
        address.setStreet("street");
        address.setState("state");
        address.setZip("zip");

        provider.setAddress(address);
        return provider;
    }
}

 

 

package a;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.beanutils.PropertyUtils;

/**
 * 
 * @author bragel
 * 
 */
public class V2Util {

    /**
     * Request1           (providerId,networkId,latitude,longitude)
     * Request2          (providerId,addressId)
     * RequestCommon     (providerId,networkId,latitude,longitude,  returnAddressId,addressId)
     * RequestCommon有以上两个类的所有属性(全集),并有returnAddressId来区分是哪一个类
     * 
     * RequestCommon -> Request1或者Request2
     * 
     * @param pi
     * @param t
     * @return
     * @throws Exception
     */
    public static <T> List<T> convert(List<RequestCommon> pi, Class<T> t) throws Exception {
        List<T> cs = new ArrayList<T>();
        for (RequestCommon p : pi) {
            T c = t.newInstance();
            PropertyUtils.copyProperties(c, p);
            cs.add(c);
        }
        return cs;
    }

    /**
     * ProviderIdentifier或者ProviderIdentifier2 -> ProviderIdentifierCommon
     * 
     * @param pi
     * @return
     * @throws Exception
     */
    public static <T> List<RequestCommon> convert(List<T> pi) throws Exception {
        List<RequestCommon> cs = new ArrayList<RequestCommon>();
        for (T p : pi) {        
            cs.add(convert(p));
        }
        return cs;
    }

    public static <T> RequestCommon convert(T p) throws Exception {
        RequestCommon c = RequestCommon.class.newInstance();
        PropertyUtils.copyProperties(c, p);
        if (c.getAddressId() != 0) {
            c.setReturnAddressId(0);
        }
        return c;
    }
    
    
    /**
     * Provider -> Provider2, Provider?
     * 注意Provider和Provider2的address不一样,
     * Provider2的Address2有更多属性
     * 既然Address和Address2是不同类型,所以它们在Provider和Provider2里就不能同名,1个叫address,1个叫address2
     * 同名不同类型时,PropertyUtils.copyProperties(c, p);会报错
     * 叫address2后,PropertyUtils.copyProperties(c, p);就不能给address2赋值,需要手动进行
     * 
     * 在Provider2里给address2默认初始化private Address2 address2 = new Address2();,  
     * 也可手动赋值,PropertyUtils.setProperty(c, "address", new Address2());
     * 然后再把Provider的address赋值给它,PropertyUtils.copyProperties(PropertyUtils.getProperty(c, "address2"), PropertyUtils.getProperty(p, "address"));
     * 
     * @param p
     * @param t
     * @return
     * @throws Exception
     */
    public static <T> T convert(Provider p, Class<T> t, int returnAddressId) throws Exception {
        T c = t.newInstance();
        PropertyUtils.copyProperties(c, p);
        if (returnAddressId == 0) {
            PropertyUtils.copyProperties(PropertyUtils.getProperty(c, "address2"), PropertyUtils.getProperty(p, "address"));
        }
        
        return c;
    }
    
    
    
    

}

 

package a;

import java.util.List;

/*
 * @author bragel
 *
 */
public class Test {

    /**
     * public <T, V> T getProvider(String clientId, V request, Class<T> t)
     * 
     * 所有要使用到的泛型都必須在public/private等之後,返回類型void/String等之前用<>定義
     * 如<T, V>
     * <T, V>只是類型定義,不是返回類型,返回類型該是String或者T還是不能少
     * @throws Exception 
     * 
     */
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        ProviderService service = new ProviderService();
        
        Request1 request1 = new Request1();
        request1.setLatitude(0d);
        request1.setLongitude(0d);
        request1.setNetworkId(1);
        request1.setProviderId(1);
  
        Request2 request2 = new Request2();
        request2.setProviderId(1);
        request2.setAddressId(1);
  
        /**
         * 实现的效果是:
         * 同一个service.getProvider()方法
         * 
         * Provider 使用request1参数来调用,得到的返回值是Provider
         * Provider2使用request2参数来调用,得到的返回值是Provider2
         */
        Provider provider = service.getProvider("clientId", request1, Provider.class);        
        Provider2 provider2 = service.getProvider("clientId", request2, Provider2.class);
        
        System.out.println(JaxbUtil.java2xml(provider, Provider.class));
        System.out.println(JaxbUtil.java2xml(provider2, Provider2.class));
        
    }

}

 

 

---------------------------------------------------------------------------------------

 

package a;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlType;

/**
 * 
 * @author bragel
 *
 */
@XmlType
@XmlAccessorType(XmlAccessType.FIELD)
public class Address {
    @XmlElement(name = "address_id")
    private int id;    
    
    @XmlElement(name = "street")
    private String street;

    @XmlElement(name = "county")
    private String county;

    @XmlElement(name = "city")
    private String city;

    @XmlElement(name = "state")
    private String state;

    @XmlElement(name = "zip")
    private String zip;
    
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getStreet() {
        return street;
    }

    public void setStreet(String street) {
        this.street = street;
    }

    public String getCounty() {
        return county;
    }

    public void setCounty(String county) {
        this.county = county;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public String getZip() {
        return zip;
    }

    public void setZip(String zip) {
        this.zip = zip;
    }
    
    public String toString() {
        return String.format("Address:id:%s;street:%s;country:%s;city:%s;state:%s;zip:%s;", id, street, county, city, state, zip);
        
    }
    

}

 

package a;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlType;


/**
 * 
 * @author bragel
 *
 */
@XmlType
@XmlAccessorType(XmlAccessType.FIELD)
public class Address2 {
    @XmlElement(name = "address_id")
    private int id;    
    
    @XmlElement(name = "street")
    private String street;

    @XmlElement(name = "county")
    private String county;

    @XmlElement(name = "city")
    private String city;

    

    
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getStreet() {
        return street;
    }

    public void setStreet(String street) {
        this.street = street;
    }

    public String getCounty() {
        return county;
    }

    public void setCounty(String county) {
        this.county = county;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    

    public String toString() {
        return String.format("Address2:id:%s;street:%s;country:%s;city:%s;", id, street, county, city);
        
    }

    
}

 

package a;

import javax.xml.bind.annotation.*;

import java.util.ArrayList;
import java.util.List;

@XmlType
@XmlAccessorType(XmlAccessType.FIELD)
public class Network {
    @XmlElement(name = "network_id")
    private int id;
    
    @XmlElement(name = "name")
    private String name;
    
    @XmlElementWrapper(name = "carrierIds")
    @XmlElement(name = "carrier_id")
    private List<Integer> carrierIds = new ArrayList<Integer>();
    
    @XmlTransient
    private int carrierGroupId;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }


    public List<Integer> getCarrierIds() {
        return carrierIds;
    }

    public void setCarrierIds(List<Integer> carrierIds) {
        this.carrierIds = carrierIds;
    }

    public int getCarrierGroupId() {
        return carrierGroupId;
    }

    public void setCarrierGroupId(int carrierGroupId) {
        this.carrierGroupId = carrierGroupId;
    }


    

}

 

package a;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.StringReader;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

public class JaxbUtil {
    
    /**
     * java -> xml String
     * 
     */
    public static String java2xml(Object obj, Class beanClass) throws Exception {
        
        JAXBContext context = JAXBContext.newInstance(beanClass);
        // 根据上下文获取marshaller对象
        Marshaller marshaller = context.createMarshaller();
        // 设置编码字符集
        marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
        // 格式化XML输出,有分行和缩进
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        // 打印到控制台
        //marshaller.marshal(obj, System.out);

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        marshaller.marshal(obj, baos);
        String xmlObj = new String(baos.toByteArray());
        return xmlObj.replace(" standalone=\"yes\"", "");
      }
      
      /**
       * java -> xml file
       * 
       */
      public static void java2xmlFile(Object obj, Class beanClass, File file) throws Exception {
        JAXBContext context = JAXBContext.newInstance(beanClass);
        // 根据上下文获取marshaller对象
        Marshaller marshaller = context.createMarshaller();
        // 设置编码字符集
        marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
        // 格式化XML输出,有分行和缩进
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        // 打印到控制台
        //marshaller.marshal(obj, System.out);
        marshaller.marshal(obj, file);
      }
      
      /**
       * xml -> java
       * 
       */
      public static <T> T xml2java(String xml, Class<T> beanClass) throws Exception {
        T bean = beanClass.newInstance();
        JAXBContext context = JAXBContext.newInstance(beanClass);
        Unmarshaller unmarshaller = context.createUnmarshaller();
        bean = (T) unmarshaller.unmarshal(new StringReader(xml));
        return bean;
      }
      
      
      /**
       * xml file -> java
       * 
       */
      public static <T> T xmlFile2java(File file, Class<T> beanClass) throws Exception {
        T bean = beanClass.newInstance();
        JAXBContext context = JAXBContext.newInstance(beanClass);
        Unmarshaller unmarshaller = context.createUnmarshaller();
        bean = (T) unmarshaller.unmarshal(file);
        return bean;
      }
      
      
}

 

因为Address2的属性是Address的子集,所以现在这样就可以了。

反之,如果Address2包含Address没有的属性,就需要跟Request一样,加一个AddressCommon了。

 

 输出:

 

<?xml version="1.0" encoding="UTF-8"?>
<provider>
    <provider_id>1</provider_id>
    <address>
        <address_id>1</address_id>
        <street>street</street>
        <county>country</county>
        <city>city</city>
        <state>state</state>
        <zip>zip</zip>
    </address>
    <networks>
        <network>
            <network_id>2</network_id>
            <carrierIds>
                <carrier_id>1</carrier_id>
                <carrier_id>2</carrier_id>
                <carrier_id>3</carrier_id>
            </carrierIds>
        </network>
        <network>
            <network_id>0</network_id>
            <carrierIds/>
        </network>
    </networks>
    <is_primary_care_physician>true</is_primary_care_physician>
</provider>

<?xml version="1.0" encoding="UTF-8"?>
<provider>
    <provider_id>1</provider_id>
    <address>
        <address_id>1</address_id>
        <street>street</street>
        <county>country</county>
        <city>city</city>
    </address>
    <networks>
        <network>
            <network_id>2</network_id>
            <carrierIds>
                <carrier_id>1</carrier_id>
                <carrier_id>2</carrier_id>
                <carrier_id>3</carrier_id>
            </carrierIds>
        </network>
        <network>
            <network_id>0</network_id>
            <carrierIds/>
        </network>
    </networks>
    <is_primary_care_physician>true</is_primary_care_physician>
</provider>

 

 

 

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