很郁闷的问题Java字符串拼接乱码

Question

出现在我的WEB项目中，我把问题化小就是这样子。
String a="中文";
String b="aaaa";
String a = new String(a.getBytes("ISO-8859-1"),
"UTF-8");
String b=new String(a.getBytes("ISO-8859-1"),
"UTF-8");
其中b来自网页页面获得
String c=a+b;
然后输出结果会产生乱码，我知道编码方式肯定不一样，但是我已经都转成UTF-8编码方式了，为什么还是出现乱码。求解

Answer 1

package servlet;import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.Iterator;
import java.util.List;import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;import check.CheckResourceName;import dao.StudentDao;
import dao.daoImpl.StudentDaoImpl;
import entity.Source;
import entity.Student;
import exceptions.DataAccessException;
import exceptions.NameExistsException;public class DoPublishSource extends HttpServlet { private String resourcePath;
private String tempResourcePath; /**
 * Constructor of the object.
 */
public DoPublishSource() {
super();
} /**
 * Destruction of the servlet. <br>
 */
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { response.setContentType("text/html;chartset=utf-8");
request.setCharacterEncoding("UTF-8");
response.setCharacterEncoding("UTF-8");
PrintWriter pw = response.getWriter();
long max_size = 16 * 1024 * 1024;
DiskFileItemFactory diskFactory = new DiskFileItemFactory();
diskFactory.setSizeThreshold(4 * 1024);
diskFactory.setRepository(new File(tempResourcePath)); ServletFileUpload upload = new ServletFileUpload(diskFactory);
upload.setSizeMax(-1);
try {
List fileItems = upload.parseRequest(request);
Iterator iter = fileItems.iterator();
while (iter.hasNext()) {
FileItem item = (FileItem) iter.next();
if (item.isFormField()) {
} else {
String fileName = item.getName();
int index = fileName.indexOf("\\");
fileName = fileName.substring(index + 1, fileName.length());
if (!CheckResourceName.checkResourceNameFormat(fileName)) {
request.setAttribute("msg", "文件名的长度在20个字符内，请改变文件名");
request.getRequestDispatcher("/WEB-INF/msg.jsp")
.forward(request, response);
return;
}
if (CheckResourceName.checkResourceNameExist(fileName)) {
request.setAttribute("msg", "文件名已经存在，请改变文件名");
request.getRequestDispatcher("/WEB-INF/msg.jsp")
.forward(request, response);
return;
}
StudentDao sd = new StudentDaoImpl();
Source source = new Source();
source.setSourceName(fileName);
source.setSid(((Student) request.getSession().getAttribute(
"student")).getId());
sd.publishSource(source);
long fileSize = item.getSize();
if ("".equals(fileName) && fileSize == 0) {
System.out.println("文件为空");
return;
}
System.out.println(fileName);
System.out.println(resourcePath);
fileName = new String(fileName.getBytes("ISO-8859-1"),
"utf-8");
String name=resourcePath + "/" + fileName;
File resourceFile = new File(name);
System.out.println(name);
// System.out.println(resourceFile.toString());
item.write(resourceFile);
pw.println("文件保存完毕！");
pw.println("文件大小为：" + fileSize);
}
}
} catch (FileUploadException e) {
e.printStackTrace();
} catch (DataAccessException e) {
e.printStackTrace();
request.setAttribute("msg", "数据库访问异常");
request.getRequestDispatcher("/WEB-INF/msg.jsp").forward(request,
response);
return;
} catch (Exception e) {
e.printStackTrace();
} } public void init() throws ServletException {
// Put your code here
} @Override
public void init(ServletConfig config) throws ServletException {
super.init(config);
resourcePath = config.getInitParameter("resourcePath");
tempResourcePath = config.getInitParameter("tempResourcePath");
ServletContext context = getServletContext();
resourcePath = context.getRealPath(resourcePath);
tempResourcePath = context.getRealPath(tempResourcePath);
try {
resourcePath = new String(resourcePath.getBytes("ISO-8859-1"),
"UTF-8");
tempResourcePath = new String(tempResourcePath
.getBytes("ISO-8859-1"), "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} if (!(new File(resourcePath)).isDirectory()) {
new File(resourcePath).mkdirs();
}
if (!(new File(tempResourcePath)).isDirectory()) {
new File(tempResourcePath).mkdirs();
}
}}
这是程序

Answer 2

file:/D:/software/apache-tomcat-6.0.29-windows-x86/apache-tomcat-6.0.29/webapps/classSystem/WEB-INF/databaseParams.xml-----
jdbc:mysql://127.0.0.1:3306/classsystem?useUnicode=true&characterEncoding=UTF-8
jdbc:mysql://127.0.0.1:3306/classsystem?useUnicode=true&characterEncoding=UTF-8
jdbc:mysql://127.0.0.1:3306/classsystem?useUnicode=true&characterEncoding=UTF-8
jdbc:mysql://127.0.0.1:3306/classsystem?useUnicode=true&characterEncoding=UTF-8
jdbc:mysql://127.0.0.1:3306/classsystem?useUnicode=true&characterEncoding=UTF-8
JavaScript的例子.zip
D:\software\apache-tomcat-6.0.29-windows-x86\apache-tomcat-6.0.29\webapps\classSystem\resourcePath
D:\software\apache-tomcat-6.0.29-windows-x86\apache-tomcat-6.0.29\webapps\classSystem\resourcePath/JavaScript???.zip
java.io.FileNotFoundException: D:\software\apache-tomcat-6.0.29-windows-x86\apache-tomcat-6.0.29\webapps\classSystem\resourcePath\JavaScript???.zip (文件名、目录名或卷标语法不正确。)
at java.io.FileOutputStream.open(Native Method)
at java.io.FileOutputStream.<init>(FileOutputStream.java:179)
at java.io.FileOutputStream.<init>(FileOutputStream.java:131)
at org.apache.commons.fileupload.disk.DiskFileItem.write(DiskFileItem.java:449)
at servlet.DoPublishSource.doPost(DoPublishSource.java:140)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:861)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1584)
at java.lang.Thread.run(Thread.java:619)

Answer 3

不知道你在运行的时候，是哪句报错了，也不知道你的项目用的是什么编码，但是有一点肯定，那就是你编码后有乱码。
你的项目是utf8的编码么？如果是，为什么要对这个编码？String a = new String(a.getBytes("ISO-8859-1"),"UTF-8");
这个本来就是uft8的编码了啊，如果不是，为什么要都转换成utf8的编码？！
String b=new String(a.getBytes("ISO-8859-1"),
"UTF-8");
你跟踪调试下，看是你转换编码前就是乱码，还是转换后才变成乱码的了...........

Answer 4

看下String a="中文";所在文件的编码格式。