Android开发疫情查询app（实例代码）

package com.Servlet;

import java.io.IOException;
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 com.Bean.worldbean;
import com.Dao.Dao;
import com.google.gson.Gson;



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

 /**
 * @see HttpServlet#HttpServlet()
 */
 public Worldservlet() {
 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
 response.setContentType("text/html;charset=UTF-8");
 request.setCharacterEncoding("UTF-8");
 String s=null;
 //获取传递过来的参数
 String date = request.getParameter("date");
 String name =request.getParameter("name");
 // Gson 谷歌推出的用于生成和解析JSON 数据格式的工具 使用时需要 导入jar 包 我的是 gson-2.6.2.jar
 Gson gson=new Gson();
 try {
 worldbean info= Dao.getinfo(date,name);
 //将数据 转换为 Json 格式
 s=gson.toJson(info);
 } catch (Exception e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 //System.out.println(s);
 //方法作用 只能打印输出文本格式的（包括html标签） 不可打印对象
 response.getWriter().write(s);

 }

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

}

package com.example.yiqingdemo;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import org.json.JSONObject;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class MainActivity extends AppCompatActivity {
EditText editTextCountry, editTextDate;
TextView textView;
Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editTextCountry = findViewById(R.id.editText4);
editTextDate = findViewById(R.id.editText3);
textView = findViewById(R.id.textView2);
button = findViewById(R.id.button);
button.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View v) {
//本机tomcat 发布的网站 其实是一个servlet 类 必须先让本机发布（启动tomcat 运行） 然后才能访问改网站
String url = "http://192.168.0.106:8080/YiQingSearch/Worldservlet?date=" + editTextDate.getText().toString() + "&name=" + editTextCountry.getText().toString();
get(url);
}
}
);
}
public void get(final String url) {
new Thread(new Runnable() {
@Override
public void run() {
HttpURLConnection connection = null;
InputStream is = null;
try {
//获取url 对象
URL Url = new URL(url);
//获取httpURlConnection 对象
connection = (HttpURLConnection) Url.openConnection();
//默认为get方法 or post
connection.setRequestMethod("GET");
//默认不使用缓存
connection.setUseCaches(false);
//设置连接超时时间 单位毫秒
connection.setConnectTimeout(10000);
//设置读取超时时间
connection.setReadTimeout(10000);
//设置是否从httpUrlConnection 读入，默认为true
connection.setDoInput(true);
//相应的码数为 200
if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
//获取输入流
is = connection.getInputStream();
//将输入流内的数据变为Sting类型数据
String info = getStringFromInputStream(is);
//转换为JSON 类型便于读取
JSONObject jsonObject = new JSONObject(info);
textView.setText(
"更新时间:" + jsonObject.getString("updatetime") +
"n确诊人数:" + jsonObject.getString("confirm")
+ "n死亡人数:" + jsonObject.getString("dead")
+ "n治愈人数:" + jsonObject.getString("heal")
);
/* //获取url 网页的源代码
BufferedReader reader= new BufferedReader(new InputStreamReader(is)); //包装字节流为字符流
StringBuilder response = new StringBuilder();
String line;
while((line = reader.readLine())!=null){
response.append(line);
}
String s = response.toString();
*/
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (connection != null) {
connection.disconnect();
}
}
}
}).start();
}
private static String getStringFromInputStream(InputStream is) throws Exception {
//定义字节数组缓存区
ByteArrayOutputStream by = new ByteArrayOutputStream();
byte[] buff = new byte[1024];
int len = -1;
while ((len = is.read(buff)) != -1) {
by.write(buff, 0, len);
}
is.close();
//将缓冲区的数据转换为 String 类型
String html = by.toString();
by.close();
return html;
}
}

<?xml version="1.0" encoding="utf-8"? 
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.yiqingdemo" 
<uses-permission android:name="android.permission.INTERNET" /  <!--联网所需要的权限-- 
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /  <!-- 主要用于管理 WIFI 连接的各方面-- 
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /  <!--主要用于监视一般网路连接 -- 
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme"
android:usesCleartextTraffic="true"  <!-- 指示应用程序是否打算使用明文网络流量 -- 
<activity android:name=".MainActivity" 
<intent-filter 
<action android:name="android.intent.action.MAIN" / 
<category android:name="android.intent.category.LAUNCHER" / 
</intent-filter 
</activity 
</application 
</manifest