JSON --- JAVA对象转换为json

 使用JSON的方法

 

JSON 即 JavaScript Object Natation，它是一种轻量级的数据交换格式，非常适合于服务器与 JavaScript 的交互。本文将快速讲解 JSON 格式，并通过代码示例演示如何分别在客户端和服务器端进行 JSON 格式数据的处理。

 

Json必需的包

commons-httpclient-3.1.jar
commons-lang-2.4.jar
commons-logging-1.1.1.jar
json-lib-2.2.3-jdk13.jar
ezmorph-1.0.6.jar
commons-collections-3.2.1.jar

以上包可以从

http://commons.apache.org/index.html

http://json-lib.sourceforge.net/

http://ezmorph.sourceforge.net/

http://morph.sourceforge.net/

http://www.docjar.com/

中下载到。

出现java.lang.NoClassDefFoundError: net/sf/ezmorph/Morpher错误是因为没有导入ezmorph.jar文件或版本不对。

出现java.lang.NoClassDefFoundError: org/apache/commons/collections/map/ListOrderedMap错误是因为没有导入commons-collections.jar文件或版本不对。

Java代码转换成json代码

1.       List集合转换成json代码

List list = new ArrayList();

list.add( "first" );

list.add( "second" );

JSONArray jsonArray2 = JSONArray.fromObject( list );

2.       Map集合转换成json代码

Map map = new HashMap();

map.put("name", "json");

map.put("bool", Boolean.TRUE);

map.put("int", new Integer(1));

map.put("arr", new String[] { "a", "b" });

map.put("func", "function(i){ return this.arr[i]; }");

JSONObject json = JSONObject.fromObject(map);

3.       Bean转换成json代码

JSONObject jsonObject = JSONObject.fromObject(new JsonBean());

4.       数组转换成json代码

boolean[] boolArray = new boolean[] { true, false, true };

JSONArray jsonArray1 = JSONArray.fromObject(boolArray);

 

5. 一般数据转换成json代码

JSONArray jsonArray3 = JSONArray.fromObject("['json','is','easy']" );

6.       beans转换成json代码

List list = new ArrayList();

JsonBean2 jb1 = new JsonBean2();

jb1.setCol(1);

jb1.setRow(1);

jb1.setValue("xx");

JsonBean2 jb2 = new JsonBean2();

jb2.setCol(2);

jb2.setRow(2);

jb2.setValue("");

list.add(jb1);

list.add(jb2);

JSONArray ja = JSONArray.fromObject(list);

评论

4 楼 zhijie_zhang 2012-10-10  

thank you.

3 楼 BenjaminLju 2010-04-05  

源码：List<ResDelagateObj> list = daoSupportTemplate.searchByClause(hql);
JSONArray array = JSONArray.fromObject(list);
异常：net.sf.json.JSONException: java.lang.reflect.InvocationTargetException
at net.sf.json.JSONObject._fromBean(JSONObject.java:738)
at net.sf.json.JSONObject.fromObject(JSONObject.java:182)
at net.sf.json.JSONObject._processValue(JSONObject.java:2426)
at net.sf.json.JSONObject._setInternal(JSONObject.java:2447)
at net.sf.json.JSONObject.setValue(JSONObject.java:1189)
at net.sf.json.JSONObject._fromMap(JSONObject.java:1069)
at net.sf.json.JSONObject.fromObject(JSONObject.java:173)
at net.sf.json.JSONObject._processValue(JSONObject.java:2426)
at net.sf.json.JSONObject._setInternal(JSONObject.java:2447)
at net.sf.json.JSONObject.setValue(JSONObject.java:1189)
at net.sf.json.JSONObject._fromBean(JSONObject.java:725)
at net.sf.json.JSONObject.fromObject(JSONObject.java:182)
at net.sf.json.JSONArray._processValue(JSONArray.java:2294)
at net.sf.json.JSONArray.processValue(JSONArray.java:2325)
at net.sf.json.JSONArray.addValue(JSONArray.java:2312)
at net.sf.json.JSONArray._fromCollection(JSONArray.java:841)
at net.sf.json.JSONArray.fromObject(JSONArray.java:137)
at net.sf.json.JSONArray.fromObject(JSONArray.java:120)
为什么会报错呢，请问？

2 楼 atgoingguoat 2010-03-28  

能不能说详细一点。

6.       beans转换成json代码

List list = new ArrayList();

JsonBean2 jb1 = new JsonBean2();

jb1.setCol(1);

jb1.setRow(1);

jb1.setValue("xx");

/**JsonBean2  结构是什么样的？ */
JsonBean2 jb2 = new JsonBean2();

jb2.setCol(2);

jb2.setRow(2);

jb2.setValue("");

list.add(jb1);

list.add(jb2);

JSONArray ja = JSONArray.fromObject(list);

1 楼 TheMatrix 2009-07-15  

请问，生成的json的属性名有“”包围，这样在treepanel能解析吗？如下：

[{"children":[{"children":[],"id":"sub1","leaf":true,"text":"子节点1"},{"children":[],"id":"sub2","leaf":true,"text":"子节点2"}],"id":"num1","leaf":false,"text":"节点1"},{"children":[{"children":[],"id":"sub1","leaf":true,"text":"子节点1"},{"children":[],"id":"sub2","leaf":true,"text":"子节点2"}],"id":"num2","leaf":false,"text":"节点2"},{"children":[{"children":[],"id":"sub1","leaf":true,"text":"子节点1"},{"children":[],"id":"sub2","leaf":true,"text":"子节点2"}],"id":"num3","leaf":false,"text":"节点3"},{"children":[{"children":[],"id":"sub1","leaf":true,"text":"子节点1"},{"children":[],"id":"sub2","leaf":true,"text":"子节点2"}],"id":"num4","leaf":false,"text":"节点4"}]