安卓访问网络，从数据库拿数据

摘要: 客户端访问请求，服务端从数据库取数据，响应给客户端，

先写服务端，首先正确导入用到的jar包，json的和MySQL连接的，

服务端就是一个负责处理数据的Servlet

package com.ww.zphdemo.web;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.json.JSONException;
import org.json.JSONObject;

import com.ww.zphdemo.util.JdbcMySQLUtil;

/**
* Servlet implementation class ZphInfoServlet
*/
@WebServlet("/ZphInfoServlet")
public class ZphInfoServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

/**
* @see HttpServlet#HttpServlet()
*/
public ZphInfoServlet() {
super();
// TODO Auto-generated constructor stub
}

/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}

/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("text/html;charset=utf-8");
response.setCharacterEncoding("utf-8");

PrintWriter out = response.getWriter();
//1.接收并判断请求
String req = request.getParameter("zphInfo");
System.out.println("客户端请求："+req);
//1.1如果请求不合法，
if (!req.equals("zphInfo")) {
out.write("{\"zphInfo\",\"请求不存在或网络故障！\"}");
}else{
//1.2如果请求合法，返回数据
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
conn = JdbcMySQLUtil.getConn();
stmt = conn.createStatement();
String sql = "select *from zph_info";
rs = stmt.executeQuery(sql);
List<Map<String, Object>> list = new ArrayList<>();
Map<String, Object> map ;
while(rs.next()){
map = new HashMap<>();
//Map<String, Object> map = new LinkedHashMap<>();
map.put("zph_id", rs.getInt(1));
map.put("zph_name", rs.getString("name"));
map.put("zph_date", rs.getDate("date"));
list.add(map);
}
JSONObject json = new JSONObject();
json.put("zph_info", list);
out.write(json.toString());
System.out.println("服务器反馈："+json.toString());
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch(JSONException e){
e.printStackTrace();
}
finally{
JdbcMySQLUtil.closeDB(rs, stmt, conn);
}

}

}

}

客户端

客户端主布局就是一个ListView，Java代码是接受json并处理

package com.ww.demo.listviewdemo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutionException;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import com.ww.demo.listviewdemo.util.HttpUtil;

import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int len = 0;  //用于记录json数组的长度
String[] zph_name = null;
String[] zph_date = null;
//接收服务器反馈
try {
JSONObject json = zphJson();
JSONArray jsonArr = (JSONArray) json.get("zph_info");
len = jsonArr.length();
zph_name = new String[len];
zph_date = new String[len];
for (int i = 0; i < len; i++) {
JSONObject js = (JSONObject) jsonArr.get(i);
zph_name[i] = (String) js.get("zph_name");
zph_date[i] = (String) js.get("zph_date");
}
System.out.println("服务器反馈的json:"+json);

} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
List<Map<String, Object>> list = new ArrayList<Map<String,Object>>();

for (int i = 0; i < len; i++) {
Map<String, Object> map = new HashMap<String, Object>();
map.put("zph_id", i+1);
map.put("zph_name", zph_name[i]);
map.put("zph_date", zph_date[i]);
list.add(map);

}
ListView lv = (ListView) findViewById(R.id.listView1);
lv.setAdapter(new SimpleAdapter(this, list, R.layout.userinfo_content,
new String[]{"zph_id","zph_name","zph_date"},
new int[]{R.id.zph_id, R.id.zph_name, R.id.zph_date}
));

lv.setOnItemClickListener(new OnItemClickListener() {

@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
Log.d("arg2:", "arg2是什么：  "+arg2);
Log.d("arg3:", "arg3代表什么："+arg3);

Toast.makeText(MainActivity.this, arg3+"被点击了", Toast.LENGTH_SHORT).show();

}
});
}

/**
* 定义发送请求的方法
* @throws ExecutionException
* @throws InterruptedException
* @throws JSONException
*
*/
private JSONObject zphJson() throws JSONException, InterruptedException, ExecutionException{
//使用map封装请求体
Map<String, String> map = new HashMap<String, String>();
map.put("zphInfo", "zphInfo");
//定义发送请求的URL
String url = HttpUtil.BASE_URL+"ZphInfoServlet";
//发送请求
return new JSONObject(HttpUtil.postRequest(url, map));
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}