Android客户端和Servlet服务器端通过JSON交互

本文结构如下:

1. android和servlet之间的直接信息传递(不通过json)

1.1 android端代码

1.2 servlet端代码

2. android和servlet之间通过json进行交互

2.1 android端代码

2.2 servlet端代码

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1. android和servlet之间的直接信息传递

在android端通过httpclient去访问服务器,发送request请求,并获取response。

在servlet端只需要简单的定义doGet方法和doPost方法即可。

1.1 android端代码

 

package com.example.helloworld;


public class MainActivity extends ActionBarActivity {

    private String responseMsg = "";
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
            
        Button button1 = (Button)findViewById(R.id.button1);
        button1.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View arg0) {                
                Thread loginThread = new Thread(new LoginThread());
                loginThread.start();
            }
        });
        
    }
    
  //发送请求的主要方法
private boolean loginServer(){ boolean loginValidate = false;
     //servlet服务器地址是 String urlStr
= "http://192.168.1.24:8080/servletTest/test"; HttpPost request = new HttpPost(urlStr); try { HttpClient client = getHttpClient(); //执行请求 HttpResponse response = client.execute(request);
        //response是servlet给出的返回结果
if(response.getStatusLine().getStatusCode() == 200){ loginValidate = true; responseMsg = EntityUtils.toString(response.getEntity()); } } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } return loginValidate; } public HttpClient getHttpClient(){ BasicHttpParams httpParams = new BasicHttpParams(); HttpConnectionParams.setConnectionTimeout(httpParams, 5*1000); HttpConnectionParams.setSoTimeout(httpParams, 10*1000); HttpClient client = new DefaultHttpClient(httpParams); return client; } class LoginThread implements Runnable{ public void run(){       boolean loginValidate = loginServer();       System.out.println("======================bool is :"+loginValidate+"----------------response: "+responseMsg); } } }

1.2 servlet端代码

package cn.dragon.servlet;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;

import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

import com.sun.corba.se.pept.transport.Connection;

public class ServletDemoFirst extends HttpServlet{
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
//        response.setContentType("text/html; charset=GB2312");
//        PrintWriter outPrintWriter = response.getWriter();
//        outPrintWriter.println("hello");
//        outPrintWriter.close();
        //Connection conn = null;
     //首先建立数据库连接
String driver = "com.mysql.jdbc.Driver"; String url = "jdbc:mysql://localhost:3306/test"; String user = "root"; String password = "admin"; PrintWriter out = response.getWriter(); //out.println("welcom"); try { Class.forName(driver); java.sql.Connection conn = DriverManager.getConnection(url, user, password); //out.println("loading success"); Statement statement = conn.createStatement();
       //进行数据库查询。 ResultSet rs
= statement.executeQuery("select * from career"); ArrayList<String> list1 = new ArrayList<String>(); while(rs.next()){ //out.println(rs.getString(1)); list1.add(rs.getString(1)); }
       //out用来向客户端返回数据。如果用网页访问这个网址,查询数据库的结果就显示在网页上,如果用android访问,就返回给android手机 out.println(list1.toString()); rs.close(); statement.close(); conn.close(); }
catch (ClassNotFoundException cnfex) { //System.err.println("装载 JDBC/ODBC 驱动程序失败。"); out.println("loading JDBC failed"); cnfex.printStackTrace(); System.exit(1); // terminate program } catch (SQLException sqlex) { //System.err.println("无法连接数据库"); out.println("can not connect to the database"); sqlex.printStackTrace(); System.exit(1); // terminate program } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
     doGet(request, response);
} }

 以上就是两部分的代码。都比较好理解,而且也给了一些注释。

==================================================================

2. 通过JSON进行客户端服务器的通讯

2.1 android端

package com.example.helloworld;


public class MainActivity extends ActionBarActivity {

    private String responseMsg = "";
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
            
        Button button1 = (Button)findViewById(R.id.button1);
        button1.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                //Intent intent = new Intent(MainActivity.this, InfoActivity.class);
                //startActivity(intent);
                Thread loginThread = new Thread(new LoginThread());
                loginThread.start();
            }
        });
        
    }
   
    public HttpClient getHttpClient(){
        BasicHttpParams httpParams = new BasicHttpParams();
        HttpConnectionParams.setConnectionTimeout(httpParams, 5*1000);
        HttpConnectionParams.setSoTimeout(httpParams, 10*1000);
        HttpClient client = new DefaultHttpClient(httpParams);
        return client;
    }
    
    private void sendJson(){
        //boolean loginValidate = false;
        String urlStr = "http://192.168.1.24:8080/servletTest/test";
        HttpPost post = new HttpPost(urlStr);
        try{
            //向服务器写json
            JSONObject json1 = new JSONObject();
            //Object email = null;
            Object email = "hlelo";
            json1.put("email", email);
            //Object pwd = null;
            Object pwd = "wodls";
            json1.put("password", pwd);
            
            System.out.println("=============="+json.toString());
            //保证json数据不是乱码
            StringEntity se = new StringEntity(json.toString());
            se.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
            post.setEntity(se);
            
            //发送json给服务器
            HttpClient httpClient = getHttpClient();
            HttpResponse httpResponse = httpClient.execute(post);
            
            /*int httpCode = httpResponse.getStatusLine().getStatusCode();
            if(httpCode == HttpURLConnection.HTTP_OK && httpResponse != null){
                //org.apache.http.Header[] headers = httpResponse.getAllHeaders();
                HttpEntity entity = httpResponse.getEntity();
                //org.apache.http.Header header = httpResponse.getFirstHeader("content-type");
                //读取服务器返回的json
                InputStream inputStream = entity.getContent();
                InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
                BufferedReader reader = new BufferedReader(inputStreamReader);
                String s;
                while((s= reader.readLine())!= null){
                    result.append(s);
                }
                reader.close();
                
                JSONObject jsonObject = new JSONObject(result.toString());
                String nameString = jsonObject.getString("email");
                String passString = jsonObject.getString("password");
                System.out.println("===============email is: "+nameString+", password is: "+passString);*/
        }catch(Exception exception){
            exception.printStackTrace();
        }
    }
    
    class LoginThread implements Runnable{
        public void run(){           
            sendJson();
        }
    }    
 }

2.2 servlet端代码

package cn.dragon.servlet;


public class ServletDemoFirst extends HttpServlet{
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
        doPost(request, response);
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
        //处理json内容
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/json");
        String acceptjson = "";
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader((ServletInputStream)request.getInputStream(), "utf-8"));
            StringBuffer sb = new StringBuffer("");
            String temp;
            while((temp = br.readLine()) != null){
                sb.append(temp);
            }
            br.close();                     
       //以上的过程都从request中读取json,并将json转换成string,这样可以显示出来。最终String类型的json就是acceptjson   acceptjson
= sb.toString(); System.out.println("=======json is==========="+acceptjson); if(acceptjson != ""){ //System.out.println("get the json successfully"); JSONObject jo = JSONObject.fromObject(acceptjson);
          //email即是android端发送过来的json当中的一个key,我们使用get方法读取对应的value System.out.println(jo.get(
"email")); } else{ System.out.println("get the json failed"); } } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } }

其实应该还有一段内容是servlet将json返还给android端,然后android端再解析出来。关于android端的解析过程在注释掉的部分中,但这段内容我还没有验证。

下面稍微补充一点关于JSONArray的内容——JSONArray如何传输与解析

/**** android: sendJson()      *****/
private void sendJson(){
        //boolean loginValidate = false;
        StringBuilder result = new StringBuilder();
        String urlStr = "http://192.168.1.24:8080/servletTest/test";
        HttpPost post = new HttpPost(urlStr);
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        //params.add(new BasicNameValuePair("name", "this is post"));
        try{
            //向服务器写json
            JSONObject json1 = new JSONObject();
            //Object email = null;
            Object email = "hlelo";
            json1.put("email", email);
            //Object pwd = null;
            Object pwd = "wodls";
            json1.put("password", pwd);
            
            JSONArray jsonArray = new JSONArray();
        //生成一个JSONARRAY并将上面的json装入其中 jsonArray.put(
0, json1); JSONObject json = new JSONObject();
        //再生成一个JSONObject,将刚才的JSONArray放入其中,再发送到服务器端  json.put(
"dao", jsonArray); System.out.println("=============="+json.toString()); //保证json数据不是乱码 StringEntity se = new StringEntity(json.toString()); se.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE, "application/json")); post.setEntity(se); //发送json给服务器 HttpClient httpClient = getHttpClient(); HttpResponse httpResponse = httpClient.execute(post); }catch(Exception exception){ exception.printStackTrace(); }
/***** servlet: doPost()  *****/
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{//处理json内容
        System.out.println("=======json is===========");
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/json");
        String acceptjson = "";
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader((ServletInputStream)request.getInputStream(), "utf-8"));
            StringBuffer sb = new StringBuffer("");
            String temp;
            while((temp = br.readLine()) != null){
                sb.append(temp);
            }
            br.close();
            acceptjson = sb.toString();
            System.out.println("=======json is==========="+acceptjson);
            if(acceptjson != ""){
                //System.out.println("get the json successfully");
          //先获取json
JSONObject jo = JSONObject.fromObject(acceptjson); //再获取json中包含的jsonarry,dao是刚才android端给出的key JSONArray ja = jo.getJSONArray("dao");
          //循环获取jsonarray中的每个json
for(int i = 0; i < ja.size(); i++){ JSONObject object = JSONObject.fromObject(ja.get(i));
             //获取json中的email值,email是json中的key
System.out.println(
"email is: "+object.get("email")); } } else{ System.out.println("get the json failed"); } } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } }

 

 

 

 

 

 

 

 

 

 

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