Merge pull request #1627 from WeiCzai/master

#5 #61 第五次实验+实验报告

students/net1814080903315/ContentProviderActivity.java

@@ -0,0 +1,91 @@
+package edu.hzuapps.androidlabs.net1814080903315;
+
+import androidx.appcompat.app.AppCompatActivity;
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.net.Uri;
+import android.os.Bundle;
+import android.view.View;
+import android.widget.EditText;
+import android.widget.Toast;
+
+import java.util.Random;
+
+public class ContentProviderActivity extends AppCompatActivity {
+
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_content_provider);
+
+        final ContentProviderActivity thisActivity = this;
+
+        // 保存图片信息
+        findViewById(R.id.button_save).setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                thisActivity.savePicture();
+            }
+        });
+
+        // 加载下一张图片信息
+        findViewById(R.id.button_next).setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                thisActivity.showNextPicture();
+            }
+        });
+
+    }
+
+    // 保存图片信息
+    private void savePicture() {
+        String name = ((EditText) findViewById(R.id.picture_name)).getText().toString();
+        String tags = ((EditText) findViewById(R.id.picture_tags)).getText().toString();
+
+        // 插入新记录
+        ContentValues picture = new ContentValues();
+        picture.put(ContentProviderOfPicture.NAME, name);
+        picture.put(ContentProviderOfPicture.TAGS, tags);
+        Uri uri = getContentResolver() // 执行插入操作
+                .insert(ContentProviderOfPicture.CONTENT_URI, picture);
+
+        Toast.makeText(getBaseContext(), //
+                "保存成功! \n" + uri.toString(), Toast.LENGTH_LONG).show();
+
+        this.showPictureInfo("", ""); // 清除内容
+    }
+
+    private void showPictureInfo(String name, String tags) {
+        ((EditText) findViewById(R.id.Picture_name)).setText(name);
+        ((EditText) findViewById(R.id.Picture_tags)).setText(tags);
+    }
+
+    // 显示下一张图片
+    private void showNextPicture() {
+        Cursor c = getContentResolver() // 执行查询
+                .query(ContentProviderOfPicture.CONTENT_URI, null, null, null, null);
+
+        // 随机取1条记录
+        int random = (new Random()).nextInt(10);
+
+        if (c.moveToFirst()) {
+            String name = "";
+            String tags = "";
+            int count = 1;
+            do {
+                name = c.getString(c.getColumnIndex(ContentProviderOfPicture.NAME));
+                tags = c.getString(c.getColumnIndex(ContentProviderOfPicture.TAGS));
+                if (count++ == random) {
+                    break;
+                }
+            } while (c.moveToNext());
+            // 显示在界面上
+            this.showPictureInfo(name, tags);
+        } else {
+            Toast.makeText(getBaseContext(), //
+                    "没有可显示的图片!", Toast.LENGTH_LONG).show();
+        }
+    }
+}

students/net1814080903315/ContentProviderOfPicture.java

@@ -0,0 +1,183 @@
+package edu.hzuapps.androidlabs.net1814080903315;
+
+import androidx.appcompat.app.AppCompatActivity;
+import android.content.ContentProvider;
+import android.content.ContentUris;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.UriMatcher;
+import android.database.Cursor;
+import android.database.SQLException;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.database.sqlite.SQLiteQueryBuilder;
+import android.net.Uri;
+import android.text.TextUtils;
+import java.util.HashMap;
+
+public class ContentProviderOfPicture extends ContentProvider {
+
+
+
+
+    static final String PROVIDER_NAME = "edu.hzuapps.androidlabs.tuku";
+    static final String URL = "content://" + PROVIDER_NAME + "/picture";
+    static final Uri CONTENT_URI = Uri.parse(URL);
+
+    static final String _ID = "_id";
+    static final String NAME = "name";
+    static final String TAGS = "tags";
+
+    static final int Picture = 1;
+    static final int Picture_ID = 2;
+
+    static final UriMatcher uriMatcher;
+
+    static {
+        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
+        uriMatcher.addURI(PROVIDER_NAME, "Picture", Picture);
+        uriMatcher.addURI(PROVIDER_NAME, "Picture/#", Picture_ID);
+    }
+
+    // 数据库相关操作
+    private SQLiteDatabase db;
+    static final String DATABASE_NAME = "tuku";
+    static final String TABLE_Picture = "Picture";
+    static final int DATABASE_VERSION = 1;
+    static final String CREATE_DB_TABLE =
+            " CREATE TABLE " + TABLE_Picture +
+                    " (_id INTEGER PRIMARY KEY AUTOINCREMENT, " +
+                    " name TEXT NOT NULL, " +
+                    " tags TEXT NOT NULL);";
+
+    /**
+     * 用于创建数据库的帮助类
+     */
+    private static class DatabaseHelper extends SQLiteOpenHelper {
+        DatabaseHelper(Context context) {
+            super(context, DATABASE_NAME, null, DATABASE_VERSION);
+        }
+
+        @Override
+        public void onCreate(SQLiteDatabase db) {
+            db.execSQL(CREATE_DB_TABLE);
+        }
+
+        @Override
+        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+            db.execSQL("DROP TABLE IF EXISTS " + TABLE_Picture);
+            // backup data, recover data
+            onCreate(db);
+        }
+    }
+
+    private static HashMap<String, String> DRESS_PROJECTION_MAP;
+
+    public ContentProviderOfPicture() {
+    }
+
+    @Override
+    public String getType(Uri uri) {switch (uriMatcher.match(uri)){
+        case Picture:
+            return "vnd.android.cursor.dir/vnd.example.students";
+        case Picture_ID:
+            return "vnd.android.cursor.item/vnd.example.students";
+
+        default:
+            throw new IllegalArgumentException("Unsupported URI: " + uri);
+    }
+    }
+
+    // 初始化内容提供器
+    @Override
+    public boolean onCreate() {
+        Context context = getContext(); // Activity
+        DatabaseHelper dbHelper = new DatabaseHelper(context);
+        // 创建可写的数据库（如果没有则新建）
+        this.db = dbHelper.getWritableDatabase(); // insert, update, delete
+        //db = dbHelper.getReadableDatabase() // query (select)
+        return (db == null) ? false : true;
+    }
+
+    // 插入|保存一条记录
+    @Override
+    public Uri insert(Uri uri, ContentValues values) {
+        long rowID = db.insert(TABLE_Picture, "", values);
+        if (rowID > 0) {
+            Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);
+            getContext().getContentResolver().notifyChange(_uri, null);
+            return _uri;
+        }
+        throw new SQLException("无法插入数据 " + uri);
+    }
+
+    // 查询记录
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection,
+                        String[] selectionArgs, String sortOrder) {
+        SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
+        qb.setTables(TABLE_Picture);
+
+        switch (uriMatcher.match(uri)) {
+            case Picture:
+                qb.setProjectionMap(DRESS_PROJECTION_MAP);
+                break;
+
+            case Picture_ID:
+                qb.appendWhere(_ID + "=" + uri.getPathSegments().get(1));
+                break;
+
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+
+        if (sortOrder == null || sortOrder == "") {
+            sortOrder = NAME;
+        }
+        Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, sortOrder);
+        c.setNotificationUri(getContext().getContentResolver(), uri);
+        return c;
+    }
+
+    @Override
+    public int update(Uri uri, ContentValues values, String selection,
+                      String[] selectionArgs) {
+        int count = 0;
+        switch (uriMatcher.match(uri)) {
+            case Picture:
+                count = db.update(TABLE_Picture, values, selection, selectionArgs);
+                break;
+
+            case Picture_ID:
+                count = db.update(TABLE_Picture, values, _ID + " = " + uri.getPathSegments().get(1) +
+                        (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""), selectionArgs);
+                break;
+
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+        getContext().getContentResolver().notifyChange(uri, null);
+        return count;
+    }
+
+    @Override
+    public int delete(Uri uri, String selection, String[] selectionArgs) {
+        int count = 0;
+        switch (uriMatcher.match(uri)) {
+            case Picture:
+                count = db.delete(TABLE_Picture, selection, selectionArgs);
+                break;
+
+            case Picture_ID:
+                String id = uri.getPathSegments().get(1);
+                count = db.delete(TABLE_Picture, _ID + " = " + id +
+                        (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""), selectionArgs);
+                break;
+
+            default:
+                throw new IllegalArgumentException("Unknown URI " + uri);
+        }
+        getContext().getContentResolver().notifyChange(uri, null);
+        return count;
+    }
+}

students/net1814080903315/activity_content_provider.xml

@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".ContentProviderActivity">
+
+    <RelativeLayout
+
+
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context="edu.hzuapps.net1814080903301.ContentProviderActivity">
+
+        <TextView
+            android:id="@+id/Picture_title"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:textSize="30dp"
+            android:text="图片信息"
+            android:layout_alignParentTop="true"
+            android:layout_centerHorizontal="true"/>
+
+        <ImageView
+            android:id="@+id/picture_cover"
+            android:layout_width="256px"
+            android:layout_height="256px"
+            android:src="@drawable/tuku"
+            android:layout_below="@+id/Picture_title"
+            android:layout_centerHorizontal="true"/>
+
+        <EditText
+            android:id="@+id/picture_name"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:hint="图片名"
+            android:layout_below="@+id/picture_cover"
+            android:layout_centerHorizontal="true"/>
+
+        <EditText
+            android:id="@+id/picture_tags"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:hint="图片备注信息"
+            android:layout_below="@+id/picture_name"
+            android:layout_centerHorizontal="true"/>
+
+        <Button
+            android:id="@+id/button_save"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="保存"
+            android:layout_below="@+id/picture_tags"
+            android:layout_alignParentLeft="true"/>
+
+        <Button
+            android:id="@+id/button_next"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="下一张图片"
+            android:layout_below="@+id/picture_tags"
+            android:layout_alignParentRight="true"/>
+
+    </RelativeLayout>
+
+</androidx.constraintlayout.widget.ConstraintLayout>