EChat(简易聊天项目)七、保存聊天记录

（二）使用LitePal数据库保存用户聊天记录

分析：

首先需要进行数据库的创建，需要一张表（自定义类HistoryChat）来保存聊天记录信息，

其次，需要将聊天的记录增加到数据库对应记录中；最后需要对数据库中对应的用户和对应的聊天记录查询，设置查询条件约束（其中包含了对用户和聊天对象和聊天记录的绑定，如点击不同好友是显示的不同的历史信息）等等。

 

主要部分代码实现：

① 由于之前已有用于存储用户名和密码的LitePal数据库，直接添加对应部分代码

litepal.xml

 

新建一个类HistoryChat

/*
  聊天记录历史记录实体类
 */
public class HistoryChat extends DataSupport{
    String sendtext;
    String receivetext;
    String Sender;
    String Receiver;
    String time;

    public String getSender() {
        return Sender;
    }

    public void setSender(String sender) {
        Sender = sender;
    }

    public String getReceiver() {
        return Receiver;
    }

    public void setReceiver(String receiver) {
        Receiver = receiver;
    }

    public String getReceivetext() {
        return receivetext;
    }

    public void setReceivetext(String receivetext) {
        this.receivetext = receivetext;
    }

    public String getSendtext() {
        return sendtext;
    }

    public void setSendtext(String sendtext) {
        this.sendtext = sendtext;
    }

    public String getTime() {
        return time;
    }

    public void setTime(String time) {
        this.time = time;
    }

}

 

② 新建一个用于展示聊天记录的HistoryActivity

public class HistoryActivity extends AppCompatActivity {

    private List msgList = new ArrayList<>();
    public String username;
    public String receiver;
    private RecyclerView msgRecyclerView;
    private MsgAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.history_layout);

        Intent intent = getIntent();
        username = intent.getStringExtra("username");
        receiver = intent.getStringExtra("receiver");

        initMsg();//写入历史记录
        msgRecyclerView = (RecyclerView) findViewById(R.id.msg_recycle_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        msgRecyclerView.setLayoutManager(layoutManager);
        adapter = new MsgAdapter(msgList);
        msgRecyclerView.setAdapter(adapter);

    }

    //数据库查找对应聊天记录
    public void initMsg() {
        List historylist = DataSupport.where("Sender = ? and Receiver = ?",username,receiver).find(HistoryChat.class);
        for (HistoryChat historychat : historylist){
            if (historychat.getReceivetext() == null) {
                String text = historychat.getSendtext();
                String time = historychat.getTime();
                Msg msg = new Msg(text + "--" + time, null, Msg.TYPE_SENT);
                msgList.add(msg);
            }
            if(historychat.getReceivetext() != null){
                String text1 = historychat.getReceivetext();
                String time1 = historychat.getTime();
                Msg msg1 = new Msg(text1 + "  --" + time1, null, Msg.TYPE_RECEIVED);
                msgList.add(msg1);
            }

        }
    }
}

③ 新建的history_layout.xml中添加代码（即原有聊天界面去掉下方发送栏即可） 

 

④在MessageActivity中进行代码修改，发送消息和设置初始消息部分添加了将数据增加到数据库中的操作

/*
   选择好友后进入的聊天界面
 */

public class MessageActivity extends AppCompatActivity {

    private List msgList = new ArrayList<>();
    private EditText inputText;
    private Button send;
    private Button more;
    public String username;
    public String receiver;

    private ImageView imageView;



    //调用系统相册-选择图片
    private static final int IMAGE = 1;

    private RecyclerView msgRecyclerView;
    private MsgAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Intent intent = getIntent();
        username = intent.getStringExtra("username");
        receiver = intent.getStringExtra("receiver");

        //将正在创建的活动添加到活动管理器中
        ActivityCollector.addActivity(this);
        setContentView(R.layout.message__layout);

        Connector.getDatabase();

        initMsg();//初始化消息数据
        //新建LitePal数据库


        inputText = (EditText) findViewById(R.id.input_text);
        send = (Button) findViewById(R.id.send);
        msgRecyclerView = (RecyclerView) findViewById(R.id.msg_recycle_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        msgRecyclerView.setLayoutManager(layoutManager);
        adapter = new MsgAdapter(msgList);
        msgRecyclerView.setAdapter(adapter);


        send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String content = inputText.getText().toString();
                if (!"".equals(content)){
                    Msg msg = new Msg(content,null,Msg.TYPE_SENT);
                    msgList.add(msg);
                    adapter.notifyItemInserted(msgList.size() - 1);//当有新消息时，刷新RecyclerView中的显示
                    msgRecyclerView.scrollToPosition(msgList.size() - 1);//将RecyclerView定位到最后一行
                    inputText.setText("");//清空输入框中的内容
                    //获取系统当前时间
                    SimpleDateFormat format = new SimpleDateFormat("yyyy.MM.dd. HH:mm:ss");
                    Date date = new Date(System.currentTimeMillis());
                    String time = format.format(date);

                    //存储数据到数据库
                    HistoryChat historyChat = new HistoryChat();
                    historyChat.setReceiver(receiver);
                    historyChat.setSender(username);
                    historyChat.setSendtext(content);
                    historyChat.setTime(time);
                    historyChat.save();
                }
            }
        });

 ...

 private void initMsg() {

        //获取系统当前时间
        SimpleDateFormat format = new SimpleDateFormat("yyyy.MM.dd. HH:mm:ss");
        Date date = new Date(System.currentTimeMillis());
        String time = format.format(date);

        Msg msg1 = new Msg("Hello guy.",null, Msg.TYPE_RECEIVED);
        msgList.add(msg1);
        HistoryChat historyChat = new HistoryChat();
        historyChat.setReceiver(receiver);
        historyChat.setSender(username);
        historyChat.setReceivetext("Hello guy.");
        historyChat.setTime(time);
        historyChat.save();

        Msg msg2 = new Msg("Hello.Who is that?",null, Msg.TYPE_SENT);
        msgList.add(msg2);
        HistoryChat historyChat1 = new HistoryChat();
        historyChat1.setReceiver(receiver);
        historyChat1.setSender(username);
        historyChat1.setSendtext("Hello.Who is that?");
        historyChat1.setTime(time);
        historyChat1.save();

        Msg msg3 = new Msg("This is Tom. Nice talking to you.",null,Msg.TYPE_RECEIVED);
        msgList.add(msg3);
        HistoryChat historyChat2 = new HistoryChat();
        historyChat2.setReceiver(receiver);
        historyChat2.setSender(username);
        historyChat2.setReceivetext("This is Tom. Nice talking to you.");
        historyChat2.setTime(time);
        historyChat2.save();
    }

...
}

 

 

运行效果（先选择聊天对象）