java中怎样反向显示字符串(包含实际开发中的例子)(转载)

法1.借助StringBuilder
String str="abcd123";
StringBuilder sb=new StringBuilder(str);
str=sb.reverse().toString;

法2.利用循环
String str="abcd123";
char[] chs=str.toCharArray();
int size=str.length();
char temp;
for(int i=0;i<size/2;i++){
temp=chs[i];
chs[i]=chs[size-1-i];
chs[size-1-i]=temp;
}
str=new String(chs);//翻转后的字符串

下面是实际开发时使用例子：

在extjs提供的HtmlEditor的基础上进行优化，原有的HtmlEditor不支持图片上传，修改后的HtmlEditor代码如下：

HTMLEditor = Ext.extend(Ext.form.HtmlEditor, {
    addImage : function() {
        var editor = this;
        var imgform = new Ext.FormPanel({
            region : 'center',
            labelWidth : 55,
            frame : true,
            bodyStyle : 'padding:5px 5px 0',
            autoScroll : true,
            border : false,
            fileUpload : true,
            items : [
                {
                    xtype : 'textfield',
                    fieldLabel : '选择文件',
                    name : 'userfile',
                    inputType : 'file',
                    allowBlank : false,
                    blankText : '文件不能为空',
                    height : 25,
                    anchor : '90%'
                }
            ],
            buttons : [
                {
                    text : '上传',
                    type : 'submit',
                    handler : function() {
                        if (!imgform.form.isValid()) {
                            return;
                        }
                        imgform.form.submit({
                            waitMsg : '正在上传',
                            url : 'EditImg.jsp',
                            success : function(form, action) {
                                var element = document.createElement("img");
                                var responseArray = Ext.util.JSON.decode(action.response.responseText);
                                if (responseArray.success) {
                                    var qty = responseArray.fileURL;   //注意此处是如何从后台jsp页面获取参数的（同时jsp页面是如何向js页面传参数的，后面的jsp页面代码有标注）
                                    element.src = qty;
                                    editor.insertAtCursor(element.outerHTML);
                                    win.hide();
                                }
                            }
                                                    });
                    }
                },
                {
                    text : '关闭',
                    type : 'submit',
                    handler : function() {
                        win.close(this);
                    }
                }
            ]
        })

        var win = new Ext.Window({
            title : "上传图片",
            width : 300,
            height : 200,
            modal : true,
            border : false,
            iconCls : "img.gif",
            layout : "fit",
            items : imgform

        });
        win.show();
    },
    createToolbar : function(editor) {
        HTMLEditor.superclass.createToolbar.call(this, editor);
        this.tb.insertButton(16, {
            cls : "x-btn-icon",
            icon : "img.gif",
            handler : this.addImage,
            scope : this
        });
    }
});
Ext.reg('StarHtmleditor', HTMLEditor);

有了以上这些，然后调用StarHtmleditor即可在原有的htmleditor组件中显示一个图片按钮控件，如果仅做这些还不够，还要看图片的存储位置，在以下jsp代码中调用了好多特殊方法，值得借鉴：

<%@ page import="static com.wlcsp.project.core.AppService.getappService" %>
<%@ page import="com.wlcsp.project.core.AppRequest" %>
<%@ page import="com.wlcsp.project.core.AppTemplate" %>
<%@ page import="com.wlcsp.project.bean.frameapp.kms.KmsDocument" %>
<%@ page import="com.wlcsp.project.bean.frameapp.kms.KmsDocumentAttachment" %>
<%@ page import="java.sql.Timestamp" %>
<%@ page import="com.wlcsp.project.biz.SMBManager" %>
<jsp:useBean id="mySmartUpload" scope="page" class="com.jspsmart.upload.SmartUpload"/>
<%
    final AppTemplate template = new AppTemplate(request, response, config, pageContext);
    final AppRequest req = new AppRequest(request);
%>
<%
    mySmartUpload.init(config);
    mySmartUpload.service(request, response);
    mySmartUpload.upload();
    String filepath = "";
    String filename = "";
    String fileurl = "";
    String name = "";
    String systemname = "";
    for (int i = 0; i < mySmartUpload.getFiles().getCount(); i++) {
        com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(i);
        if (!myFile.isMissing()) {
            filename = myFile.getFileName();
            name = myFile.getFileName();
            int filesize = myFile.getSize();
            Timestamp timestamp = new Timestamp(System.currentTimeMillis());
            java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("yyyyMMdd");
            String creattime = sdf.format(timestamp);
            systemname = creattime + name;
            myFile.saveAs("/docfile/kms/" + systemname);
            String s = template.getRealPath("/");
            StringBuilder sb = new StringBuilder(s);
            s = sb.reverse().toString();
            s = s.substring(2, s.length());
            sb = new StringBuilder(s);
            s = sb.reverse().toString();
            String path = SMBManager.getConfig().getKmsfile();
            String templateFileName = s + path;
            templateFileName = templateFileName + systemname;
            templateFileName = templateFileName.replace("\\", "/");
            fileurl = "E:/svn/new/Project/web/docfile/kms/" + systemname;
            out.print("{success:true,fileURL:'" + templateFileName + "'}");
        }
    }

%>

replace和replaceAll是JAVA中常用的替换字符的方法,它们的区别是: 

1)replace的参数是char和CharSequence,即可以支持字符的替换,也支持字符串的替换(CharSequence即字符串序列的意思,说白了也就是字符串); 
2)replaceAll的参数是regex,即基于规则表达式的替换,比如,可以通过replaceAll("\\d", "*")把一个字符串所有的数字字符都换成星号; 

    相同点是都是全部替换,即把源字符串中的某一字符或字符串全部换成指定的字符或字符串,如果只想替换第一次出现的,可以使用 replaceFirst(),这个方法也是基于规则表达式的替换,但与replaceAll()不同的是,只替换第一次出现的字符串; 
    另外,如果replaceAll()和replaceFirst()所用的参数据不是基于规则表达式的,则与replace()替换字符串的效果是一样的,即这两者也支持字符串的操作; 
    还有一点注意:执行了替换操作后,源字符串的内容是没有发生改变的. 

举例如下: 
        
        String src = new String("ab43a2c43d"); 

        System.out.println(src.replace("3","f"));=>ab4f2c4fd. 
        System.out.println(src.replace('3','f'));=>ab4f2c4fd. 
        System.out.println(src.replaceAll("\\d","f"));=>abffafcffd. 
        System.out.println(src.replaceAll("a","f"));=>fb43fc23d. 
        System.out.println(src.replaceFirst("\\d,"f"));=>abf32c43d 
        System.out.println(src.replaceFirst("4","h"));=>abh32c43d. 


如何将字符串中的"\"替换成"\\"： 

        String msgIn; 
        String msgOut; 
        msgOut=msgIn.replaceAll("\\\\","\\\\\\\\"); 
原因： 
         '\'在java中是一个转义字符，所以需要用两个代表一个。例如System.out.println( "\\" ) ;只打印出一个"\"。但是'\'也是正则表达式中的转义字符（replaceAll 的参数就是正则表达式），需要用两个代表一个。所以：\\\\被java转换成\\,\\又被正则表达式转换成\。 
同样 
        CODE: \\\\\\\\ 
        Java: \\\\ 
        Regex: \\ 


将字符串中的'/'替换成'\'的几种方式: 

msgOut= msgIn.replaceAll("/", "\\\\"); 
         msgOut= msgIn.replace("/", "\\"); 
         msgOut= msgIn.replace('/', '\\');