2022-11-22学习内容-Client端代码编写-数据删除

1.Client端代码编写

1.1activity_content_write.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="5dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="姓名："
            android:textColor="@color/black"
            android:textSize="17sp" />

        <EditText
            android:id="@+id/et_name"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginTop="3dp"
            android:layout_marginBottom="3dp"
            android:layout_weight="1"
            android:background="@drawable/editext_selector"
            android:hint="请输入姓名"
            android:inputType="text"
            android:maxLength="12"
            android:text="Jack"
            android:textColor="@color/black"
            android:textSize="17sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/tv_age"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="年龄："
            android:textColor="@color/black"
            android:textSize="17sp" />

        <EditText
            android:id="@+id/et_age"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginTop="3dp"
            android:layout_marginBottom="3dp"
            android:layout_weight="1"
            android:background="@drawable/editext_selector"
            android:hint="请输入年龄"
            android:inputType="number"
            android:maxLength="2"
            android:text="18"
            android:textColor="@color/black"
            android:textSize="17sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/tv_height"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="身高："
            android:textColor="@color/black"
            android:textSize="17sp" />

        <EditText
            android:id="@+id/et_height"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginTop="3dp"
            android:layout_marginBottom="3dp"
            android:layout_weight="1"
            android:background="@drawable/editext_selector"
            android:hint="请输入身高"
            android:inputType="number"
            android:maxLength="3"
            android:text="180"
            android:textColor="@color/black"
            android:textSize="17sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/tv_weight"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="体重："
            android:textColor="@color/black"
            android:textSize="17sp" />

        <EditText
            android:id="@+id/et_weight"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginTop="3dp"
            android:layout_marginBottom="3dp"
            android:layout_weight="1"
            android:background="@drawable/editext_selector"
            android:hint="请输入体重"
            android:inputType="numberDecimal"
            android:maxLength="5"
            android:text="180"
            android:textColor="@color/black"
            android:textSize="17sp" />
    </LinearLayout>

    <CheckBox
        android:id="@+id/ck_married"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="false"
        android:gravity="center"
        android:text="已婚"
        android:textColor="@color/black"
        android:textSize="17sp" />

    <Button
        android:id="@+id/btn_save"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="保存"
        android:textColor="@color/black"
        android:textSize="17sp" />

    <Button
        android:id="@+id/btn_read"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="读取"
        android:textColor="@color/black"
        android:textSize="17sp" />

    <Button
        android:id="@+id/btn_delete"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="删除"
        android:textColor="@color/black"
        android:textSize="17sp" />

</LinearLayout>

1.2ContentWriteActivity.java

package com.example.chapter07_client;

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.content.ContentValues;
import android.database.Cursor;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.CheckBox;
import android.widget.EditText;

import com.example.chapter07_client.entity.User;
import com.example.chapter07_client.util.ToastUtil;

public class ContentWriteActivity extends AppCompatActivity implements View.OnClickListener{

    private EditText et_name;
    private EditText et_age;
    private EditText et_height;
    private EditText et_weight;
    private CheckBox ck_married;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_content_write);

        et_name = findViewById(R.id.et_name);
        et_age = findViewById(R.id.et_age);
        et_height = findViewById(R.id.et_height);
        et_weight = findViewById(R.id.et_weight);
        ck_married = findViewById(R.id.ck_married);

        findViewById(R.id.btn_save).setOnClickListener(this);
        findViewById(R.id.btn_delete).setOnClickListener(this);
        findViewById(R.id.btn_read).setOnClickListener(this);
    }

    @SuppressLint("Range")
    @Override
    public void onClick(View v) {
        switch(v.getId()) {
            case R.id.btn_save:
                ContentValues values = new ContentValues();
                values.put(UserInfoContent.USER_NAME, et_name.getText().toString());
                values.put(UserInfoContent.USER_AGE, Integer.parseInt(et_age.getText().toString()));
                values.put(UserInfoContent.USER_HEIGHT, Integer.parseInt(et_height.getText().toString()));
                values.put(UserInfoContent.USER_WEIGHT, Float.parseFloat(et_weight.getText().toString()));
                values.put(UserInfoContent.USER_MARRIED, ck_married.isChecked());
                getContentResolver().insert(UserInfoContent.CONTENT_URI, values);
                ToastUtil.show(this, "保存成功");
                break;
            case R.id.btn_read:
                Cursor cursor = getContentResolver().query(UserInfoContent.CONTENT_URI, null, null, null, null);
                if (cursor != null) {
                    while(cursor.moveToNext()) {
                        User info = new User();
                        info.id = cursor.getInt(cursor.getColumnIndex(UserInfoContent._ID));
                        info.name = cursor.getString(cursor.getColumnIndex(UserInfoContent.USER_NAME));
                        info.age = cursor.getInt(cursor.getColumnIndex(UserInfoContent.USER_AGE));
                        info.height = cursor.getInt(cursor.getColumnIndex(UserInfoContent.USER_HEIGHT));
                        info.weight = cursor.getFloat(cursor.getColumnIndex(UserInfoContent.USER_WEIGHT));
                        info.married = cursor.getInt(cursor.getColumnIndex(UserInfoContent.USER_MARRIED)) == 1 ? true : false;
                        Log.d("ning", info.toString());
                    }
                    cursor.close();
                }
                break;
        }
    }
}

1.3UserInfoContent.java

package com.example.chapter07_client;

import android.net.Uri;
import android.provider.BaseColumns;

public class UserInfoContent implements BaseColumns {

    public static final String AUTHORITIES = "com.example.chapter07_server.provider.UserInfoProvider";

    // content://com.example.chapter07_server.provider.UserInfoProvider

    // 访问内容提供器的URI
    public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITIES + "/user");

    // 下面是该表的各个字段名称
    public static final String USER_NAME = "name";
    public static final String USER_AGE = "age";
    public static final String USER_HEIGHT = "height";
    public static final String USER_WEIGHT = "weight";
    public static final String USER_MARRIED = "married";

}

1.4效果：

先启动server端：

控制台输出：

D/ning: UserInfoProvider onCreate

再启动client：

点“保存”：

控制台输出：

D/ning: UserInfoProvider insert

再点“读取”：控制台输出：

D/ning: UserInfoProvider query
D/ning: User{id=1, name='Jack', age=18, height=180, weight=180.0, married=false}

再点击“保存”、“读取”，控制台输出：

D/ning: UserInfoProvider query
D/ning: User{id=1, name='Jack', age=18, height=180, weight=180.0, married=false}
D/ning: User{id=2, name='Jack', age=18, height=180, weight=180.0, married=false}

2.数据删除

2.1chapter07-server应用的UserInfoProvider.java新增内容：

private static final UriMatcher URI_MATCHER = new UriMatcher(UriMatcher.NO_MATCH);

private static final int USERS = 1;
private static final int USER = 2;

static {
    // 往Uri匹配器中添加指定的数据路径
    URI_MATCHER.addURI(UserInfoContent.AUTHORITIES, "/user", USERS);
    URI_MATCHER.addURI(UserInfoContent.AUTHORITIES, "/user/#", USER);
}

// content://com.example.chapter07_server.provider.UserInfoProvider/user
@Override
public Uri insert(Uri uri, ContentValues values) {
    Log.d("ning", "UserInfoProvider insert");
    if (URI_MATCHER.match(uri) == USERS) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        db.insert(UserDBHelper.TABLE_NAME, null, values);
    }
    return uri;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection,
                    String[] selectionArgs, String sortOrder) {
    Log.d("ning", "UserInfoProvider query");
    if (URI_MATCHER.match(uri) == USERS) {
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        return db.query(UserDBHelper.TABLE_NAME, projection, selection, selectionArgs, null, null, null);
    }
    return null;
}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
    int count = 0;
    switch (URI_MATCHER.match(uri)) {
        // content://com.example.chapter07_server.provider.UserInfoProvider/user
        // 删除多行
        case USERS:
            SQLiteDatabase db1 = dbHelper.getWritableDatabase();
            count = db1.delete(UserDBHelper.TABLE_NAME, selection, selectionArgs);
            db1.close();
            break;
        // content://com.example.chapter07_server.provider.UserInfoProvider/user/2
        // 删除单行
        case USER:
            String id = uri.getLastPathSegment();
            SQLiteDatabase db2 = dbHelper.getWritableDatabase();
            count = db2.delete(UserDBHelper.TABLE_NAME, "_id=?", new String[]{id});
            db2.close();
            break;
    }

    return count;
}

2.2charpter07-client应用的清单文件，新增内容：

<!-- 出于安全考虑，Android 11 要求应用事先说明需要访问的其他软件包 -->
    <queries>
        <package android:name="com.example.chapter07_server"/>
    </queries>

2.3charpter07-client应用的ContentWriteActivity.java中新增内容：

@SuppressLint("Range")
    @Override
    public void onClick(View v) {
        switch(v.getId()) {
            case R.id.btn_save:
                ContentValues values = new ContentValues();
                values.put(UserInfoContent.USER_NAME, et_name.getText().toString());
                values.put(UserInfoContent.USER_AGE, Integer.parseInt(et_age.getText().toString()));
                values.put(UserInfoContent.USER_HEIGHT, Integer.parseInt(et_height.getText().toString()));
                values.put(UserInfoContent.USER_WEIGHT, Float.parseFloat(et_weight.getText().toString()));
                values.put(UserInfoContent.USER_MARRIED, ck_married.isChecked());
                getContentResolver().insert(UserInfoContent.CONTENT_URI, values);
                ToastUtil.show(this, "保存成功");
                break;
            case R.id.btn_read:
                Cursor cursor = getContentResolver().query(UserInfoContent.CONTENT_URI, null, null, null, null);
                if (cursor != null) {
                    while(cursor.moveToNext()) {
                        User info = new User();
                        info.id = cursor.getInt(cursor.getColumnIndex(UserInfoContent._ID));
                        info.name = cursor.getString(cursor.getColumnIndex(UserInfoContent.USER_NAME));
                        info.age = cursor.getInt(cursor.getColumnIndex(UserInfoContent.USER_AGE));
                        info.height = cursor.getInt(cursor.getColumnIndex(UserInfoContent.USER_HEIGHT));
                        info.weight = cursor.getFloat(cursor.getColumnIndex(UserInfoContent.USER_WEIGHT));
                        info.married = cursor.getInt(cursor.getColumnIndex(UserInfoContent.USER_MARRIED)) == 1 ? true : false;
                        Log.d("ning", info.toString());
                    }
                    cursor.close();
                }
                break;
            case R.id.btn_delete:

                // 单行删除：
                // content://com.example.chapter07_server.provider.UserInfoProvider/user/2
//                Uri uri = ContentUris.withAppendedId(UserInfoContent.CONTENT_URI, 10);
//                int count = getContentResolver().delete(uri, null, null);

                // 多行删除：
                // content://com.example.chapter07_server.provider.UserInfoProvider/user
                int count = getContentResolver().delete(UserInfoContent.CONTENT_URI, "name=?", new String[]{"Jack"});
                if (count > 0) {
                    ToastUtil.show(this, "删除成功");
                }
                break;
        }
    }

2.4charpter07-client及charpter07-server应用的UserInfoContent.java新增内容：

public static final String AUTHORITIES = "com.example.chapter07_server.provider.UserInfoProvider";

    // content://com.example.chapter07_server.provider.UserInfoProvider

    // 访问内容提供器的URI
    public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITIES + "/user");

2.5效果：

2.5.1单条删除：

点“读取”：

D/ning: User{id=8, name='Jack', age=18, height=180, weight=180.0, married=false}
D/ning: User{id=9, name='Jack', age=18, height=180, weight=180.0, married=false}
D/ning: User{id=10, name='Jack', age=18, height=180, weight=180.0, married=false}
D/ning: User{id=11, name='Jack', age=18, height=180, weight=180.0, married=false}

点“删除”，删除id=10的，再点“读取”，可以看到id=10的已经被删除了：

D/ning: User{id=8, name='Jack', age=18, height=180, weight=180.0, married=false}
D/ning: User{id=9, name='Jack', age=18, height=180, weight=180.0, married=false}
D/ning: User{id=11, name='Jack', age=18, height=180, weight=180.0, married=false}

2.5.2多条删除：

点“读取”：

D/ning: User{id=8, name='Jack', age=18, height=180, weight=180.0, married=false}
D/ning: User{id=9, name='Jack', age=18, height=180, weight=180.0, married=false}
D/ning: User{id=11, name='Jack', age=18, height=180, weight=180.0, married=false}

点“删除”，删除所有名字等于"Jack"的，再点“读取”，可以看到全都删除了（因为名字都等于Jack）：

（备注：这里直接点“读取”，会报WaitForGcToComplete blocked Instrumentation on None for 6.246ms。所以我采用先点一下“保存”，再点“读取”的方式。查出来id=12，说明点击“删除”时，当时所有name=Jack的记录即id=8,9,11的，已经都被删掉了。）

D/ning: User{id=12, name='Jack', age=18, height=180, weight=180.0, married=false}