Java实现app接口和Socket消息传递(11)获取在线用户列表

原创：http://blog.csdn.net/iwanghang

其实，一般的App来说学到这里，足够应付一般的接口了。

但是，我们目标是除了接口还有Socket通讯，所以。。。路漫漫啊。。。。

1.先看一下App端的GIF效果

2.为了方便测试，我们手动修改一下数据库

把一部分id改成online为1

2.我们增加了一个接口

用于App端获取在线用户

package com.iwanghang.servletDemo;import java.io.IOException;import java.io.PrintWriter;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.logging.Level;import java.util.logging.Logger;import javax.servlet.Servlet;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;public class UserOnline implements Servlet{private String date; // 返回的Json数据public UserOnline() {System.out.println("HelloServlet...");}@Overridepublic void destroy() {System.out.println("destroy...");}@Overridepublic ServletConfig getServletConfig() {System.out.println("getServletConfig...");return null;}@Overridepublic String getServletInfo() {System.out.println("getServletInfo...");return null;}@Overridepublic void init(ServletConfig arg0) throws ServletException {System.out.println("init...");}@Overridepublic void service(ServletRequest request, ServletResponse response) throws ServletException, IOException {System.out.println("service...");/** * 查询在线用户username的sql语句如下 * select * from aaa_user where `online` = '1' * select * from aaa_user where online = '1' * select username from aaa_user where online = '1' * 我们用最后一个 */        try {                Class.forName("com.mysql.jdbc.Driver");//创建驱动器               // 写法1. 这样写会有警告，但是不影响使用              // Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/mysql","root","123456");//这是数据库的路径，并且还有输入账号（一般默认是root），密码之前创建用户时的那个                // 写法2. 看起来比较复杂，但是没有警告              Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/demo1113?useUnicode=true&characterEncoding=utf-8&useSSL=false","root", "123456");              PreparedStatement pst = con.prepareCall("select username from aaa_user where online = '1'");//输入的是要在MySQL中执行的代码                ResultSet rs = pst.executeQuery();//获得执行上面代码后的结果集               date =  "[";            while(rs.next()){                String username = rs.getString("username");              System.out.println("username = " + username);            date = date + "{\"username\":\"" + username+"\"},";            }            date = date.substring(0, date.length()-1); // 截取字符串，从第1个字符串开始，截取至，倒数第2个。也就是，去掉最后一个","    date =  date + "]";            }        catch (ClassNotFoundException ex) {            Logger.getLogger(UserOnline.class.getName()).log(Level.SEVERE, null, ex);        } catch (SQLException ex) {            Logger.getLogger(UserOnline.class.getName()).log(Level.SEVERE, null, ex);        }                    // 如果date长度小于3，可以认为没有数据，给date赋值no，告诉App没有数据        if (date.length()<3) {        //System.out.println("date.length() = " + date.length());        date = "no";        }        System.out.println("date = " + date);                response.setCharacterEncoding("UTF-8");response.setContentType("application/json; charset=utf-8");String jsonStr = date;PrintWriter out = null;try {    out = response.getWriter();    out.write(jsonStr);} catch (IOException e) {    e.printStackTrace();} finally {    if (out != null) {        out.close();    }}}}

同时，不要忘记在web.xml里做映射

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">  <!-- Servlet 配置 -->  <servlet><!-- Servlet 注册的名字 --><servlet-name>test01</servlet-name><!-- Servlet 全类名 --><servlet-class>com.iwanghang.servletDemo.Test01</servlet-class><!-- Servlet 创建邮件级别 0为最先创建 --><load-on-startup>1</load-on-startup>  </servlet>  <!-- Servlet 映射 -->  <servlet-mapping><!-- 映射 配置中一个同名节点 --><servlet-name>test01</servlet-name><!-- 映射 具体的访问路径  --><url-pattern>/test01</url-pattern>  </servlet-mapping>            <!-- Servlet 配置 -->  <servlet><!-- Servlet 注册的名字 --><servlet-name>useronline</servlet-name><!-- Servlet 全类名 --><servlet-class>com.iwanghang.servletDemo.UserOnline</servlet-class><!-- Servlet 创建邮件级别 0为最先创建 --><load-on-startup>1</load-on-startup>  </servlet>  <!-- Servlet 映射 -->  <servlet-mapping><!-- 映射 配置中一个同名节点 --><servlet-name>useronline</servlet-name><!-- 映射 具体的访问路径  --><url-pattern>/useronline</url-pattern>  </servlet-mapping></web-app>

3.接下来，我们看一看App端的几个Activity

MainActivity：

package com.iwanghang.demo1114;import android.app.Activity;import android.content.Intent;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 android.widget.Toast;import com.android.volley.AuthFailureError;import com.android.volley.Request;import com.android.volley.RequestQueue;import com.android.volley.Response;import com.android.volley.VolleyError;import com.android.volley.toolbox.StringRequest;import com.android.volley.toolbox.Volley;import org.json.JSONException;import org.json.JSONObject;import java.util.HashMap;import java.util.Map;import static com.iwanghang.demo1114.Constant.LOGINCHECK;public class MainActivity extends Activity {    private String TAG = "MainActivity";    // 创建请求队列    RequestQueue requestQueue = null;    private EditText et_username;    private EditText et_password;    private Button bt_login;    private TextView tv_log;    private String username;    private String password;    private String islogin;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        requestQueue = Volley.newRequestQueue(this);        et_username = findViewById(R.id.et_username);        et_password = findViewById(R.id.et_password);        bt_login = findViewById(R.id.bt_login);        tv_log = findViewById(R.id.tv_log);        initLogin(); // 登录 按钮点击事件监听    }    /**     * 登录 按钮点击事件监听     */    private void initLogin() {        bt_login.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                // 获取输入账号密码                username = et_username.getText().toString();                password = et_password.getText().toString();                Log.v(TAG, " username = " + username);                netLogin(); // 发送网络请求            }        });    }    /**     * 发送网络请求 尝试登陆     */    private void netLogin() {        // 请求地址        //String url = "hhttp://192.168.1.129:8080/servletDemo/test01";        StringRequest request = new StringRequest(Request.Method.POST, LOGINCHECK, new Response.Listener<String>() {            @Override            public void onResponse(String response) {                Log.v(TAG,"response = " + response);// 返回结果                try {                    if (response.equals("no")){                        Toast.makeText(MainActivity.this, "登录失败，请检查ID是否正确", Toast.LENGTH_SHORT).show();                    }else {                        JSONObject object1 = new JSONObject(response);                        islogin = object1.getString("islogin"); // islogin                        Log.e("TAG", "islogin = " + islogin);                        Toast.makeText(MainActivity.this, "islogin = " + islogin, Toast.LENGTH_SHORT).show();                        if (islogin.equals("yes")){                            tv_log.setText("登录成功");                            goListActivity(username); // 跳转到 在线 且 不在会话中 的用户列表 Activity                        }else if (islogin.equals("no")) {                            tv_log.setText("登录失败");                        }                    }                } catch (JSONException e) {                    e.printStackTrace();                }            }        }, new Response.ErrorListener() {            @Override            public void onErrorResponse(VolleyError error) {                Log.v(TAG,"error = " + error); // 错误结果                Toast.makeText(getApplication(),"网络出问题",Toast.LENGTH_SHORT).show();            }        }){            @Override            protected Map<String, String> getParams() throws AuthFailureError {                // 请求的内容                Map<String,String> params = new HashMap<>();                params.put("username",username);                params.put("password",password);                return params;            }        };        // 添加到请求队列        requestQueue.add(request);    }    /**     * 跳转到 在线 且 不在会话中 的用户列表 Activity     */    private void goListActivity(String username) {        Intent intent = new Intent(MainActivity.this, ListActivity.class);        intent.putExtra("username",username); // 姓名        startActivity(intent);    }}

ListActivity：

package com.iwanghang.demo1114;import android.app.Activity;import android.content.Context;import android.content.Intent;import android.os.Bundle;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.Button;import android.widget.ListView;import android.widget.TextView;import android.widget.Toast;import com.android.volley.AuthFailureError;import com.android.volley.Request;import com.android.volley.RequestQueue;import com.android.volley.Response;import com.android.volley.VolleyError;import com.android.volley.toolbox.StringRequest;import com.android.volley.toolbox.Volley;import org.json.JSONArray;import org.json.JSONException;import org.json.JSONObject;import java.util.ArrayList;import java.util.HashMap;import java.util.Map;import static com.iwanghang.demo1114.Constant.USERLIST;public class ListActivity extends Activity {    private String TAG = "ListActivity";    // 创建请求队列    RequestQueue requestQueue = null;    private TextView tv_name;    private Button bt_getList;    private String username;    private String usernameArray;    private ListAdapter adapter;    private ListView lv_main;    private ArrayList<String> list = new ArrayList<String>();    private String clickName = "noData"; // 获取点击的字符串    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_list);        requestQueue = Volley.newRequestQueue(this);        // 接过来传递的值        Bundle extras = getIntent().getExtras();        username = extras.getString("username");        tv_name = findViewById(R.id.tv_name);        tv_name.setText(username);        bt_getList = findViewById(R.id.bt_getList);        initList(); // 获取 在线 且 不在会话中 的用户列表 按钮点击事件监听        lv_main = findViewById(R.id.lv_main);        adapter = new ListAdapter();    }    /**     * 获取 在线 且 不在会话中 的用户列表 按钮点击事件监听     */    private void initList() {        bt_getList.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                getList(); // 发送网络请求            }        });    }    /**     * 获取 在线 且 不在会话中 的用户列表     */    private void getList() {        // 请求地址        //String url = "http://192.168.1.111:8001/app_new/user_sc.asp";        StringRequest request = new StringRequest(Request.Method.POST, USERLIST, new Response.Listener<String>() {            @Override            public void onResponse(String response) {                Log.v(TAG,"response = " + response);// 返回结果                try {                    if (response.equals("no")){                        Toast.makeText(ListActivity.this, "登录失败，请检查ID是否正确", Toast.LENGTH_SHORT).show();                    }else {                        JSONArray jsonArray = new JSONArray(response.toString());                        Toast.makeText(ListActivity.this, "response.jsonArray.toString() = " + jsonArray, Toast.LENGTH_SHORT).show();                        usernameArray = "";                        for(int i=0;i<jsonArray.length();i++)                        {                            JSONObject jsonObject = jsonArray.getJSONObject(i);                            Log.e("TAG", jsonObject.getString("username"));                            String username = jsonObject.getString("username");                            if (usernameArray == "") {                                usernameArray = usernameArray + username;                            }else{                                usernameArray = usernameArray +"," + username;                            }                        }                        Toast.makeText(ListActivity.this, "在线 且 不在会话中 的用户列表 = " + usernameArray, Toast.LENGTH_SHORT).show();                        initListData(); // 初始化列表数据                    }                } catch (JSONException e) {                    e.printStackTrace();                }            }        }, new Response.ErrorListener() {            @Override            public void onErrorResponse(VolleyError error) {                Log.v(TAG,"error = " + error); // 错误结果                Toast.makeText(getApplication(),"网络出问题",Toast.LENGTH_SHORT).show();            }        }){            @Override            protected Map<String, String> getParams() throws AuthFailureError {                // 请求的内容                Map<String,String> params = new HashMap<>();                params.put("username",username);                return params;            }        };        // 添加到请求队列        requestQueue.add(request);    }    /**     * 初始化列表数据     */    private void initListData() {        String temp = null;        list.clear();        String[] temp_all = usernameArray.split(",");        for (int i = 0 ; i <temp_all.length ; i++ ) { // 遍历数据            temp = temp_all[i];            list.add(temp);        }        lv_main.setAdapter(adapter);    }    private class ListAdapter extends BaseAdapter {        private LayoutInflater mInflater;        ListAdapter() {            mInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);        }        @Override        public int getCount() {            // TODO Auto-generated method stub            return list.size();        }        @Override        public Object getItem(int position) {            // TODO Auto-generated method stub            return list.get(position);        }        @Override        public long getItemId(int position) {            // TODO Auto-generated method stub            return position;        }        @Override        public View getView(final int position, View convertView, ViewGroup parent) {            // TODO Auto-generated method stub            System.out.println("getView " + position + "    " + convertView);            ListActivity.viewHolder holder = null;            if (convertView == null) {                convertView = mInflater.inflate(R.layout.item_list, null);                holder = new viewHolder();                holder.text = convertView.findViewById(R.id.text);                convertView.setTag(holder);            } else {                holder = (ListActivity.viewHolder) convertView.getTag();            }            Log.v(TAG,""+ list.get(position));            holder.text.setText(list.get(position));            holder.text.setOnClickListener(new View.OnClickListener() {                @Override                public void onClick(View v) {                    clickName = list.get(position);                    Log.v(TAG,"text OnClickListener = " + clickName);                    Toast.makeText(ListActivity.this, clickName, Toast.LENGTH_SHORT).show();                    goCallActivity(username,clickName); // 跳转到 视频通话请求页面                }            });            return convertView;        }    }    /**     * 使用一个类来保存Item中的元素     */    public static class viewHolder {        public TextView text;    }    /**     * 跳转到 视频通话请求页面     */    private void goCallActivity(String username,String clickName) {        Intent intent = new Intent(ListActivity.this, CallActivity.class);        intent.putExtra("username",username); // 姓名        intent.putExtra("clickName",clickName); // 对方        startActivity(intent);    }}

CallActivity：

package com.iwanghang.demo1114;import android.app.Activity;import android.os.Bundle;import android.widget.ImageView;import android.widget.TextView;public class CallActivity extends Activity {    private String TAG = "CallActivity";    private TextView tv_i;    private TextView tv_u;    private ImageView iv_call;    private TextView tv_log;    private String username;    private String clickName;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_call);        tv_i = findViewById(R.id.tv_i);        tv_u = findViewById(R.id.tv_u);        iv_call = findViewById(R.id.iv_call);        tv_log = findViewById(R.id.tv_log);        // 接过来传递的值        Bundle extras = getIntent().getExtras();        username = extras.getString("username");        clickName = extras.getString("clickName");        tv_i.setText(username);        tv_u.setText(clickName);    }}

原创：http://blog.csdn.net/iwanghang