contentProvider

最新推荐文章于 2024-08-01 09:28:45 发布

转载最新推荐文章于 2024-08-01 09:28:45 发布 · 754 阅读

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

/**
 * @author 郭宏志
 * 通讯录常量类
 */
public final class Employees {
	// 授权常量
    public static final String AUTHORITY = "com.amaker.provider.Employees";
    private Employees() {}
    // 内部类
    public static final class Employee implements BaseColumns {
    	// 构造方法
        private Employee() {}
        // 访问Uri
        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/employee");
        // 内容类型
        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.amaker.employees";
        public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/vnd.amaker.employees";
        
        // 默认排序常量
        public static final String DEFAULT_SORT_ORDER = "name DESC";// 按姓名排序
        // 表字段常量
        public static final String NAME = "name";					// 姓名
        public static final String GENDER= "gender";				// 性别
        public static final String AGE = "age"; 					// 年龄
    }
}

package com.amaker.ch10.app;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import com.amaker.ch10.app.Employees.Employee;/** * * @author 郭宏志 * 数据库工具类 */public class DBHelper extends SQLiteOpenHelper{ // 数据库名称常量 private static final String DATABASE_NAME = "Employees.db"; // 数据库版本常量 private static final int DATABASE_VERSION = 1; // 表名称常量 public static final String EMPLOYEES_TABLE_NAME = "employee";// 构造方法public DBHelper(Context context) {// 创建数据库super(context, DATABASE_NAME,null, DATABASE_VERSION);}// 创建时调用public void onCreate(SQLiteDatabase db) { db.execSQL("CREATE TABLE " + EMPLOYEES_TABLE_NAME + " (" + Employee._ID + " INTEGER PRIMARY KEY," + Employee.NAME + " TEXT," + Employee.GENDER + " TEXT," + Employee.AGE + " INTEGER" + ");");}// 版本更新时调用public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// 删除表db.execSQL("DROP TABLE IF EXISTS employee"); onCreate(db);}}

package com.amaker.ch10.app;

import java.util.HashMap;

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.text.TextUtils;

import com.amaker.ch10.app.Employees.Employee;

public class EmployeeProvider extends ContentProvider{
	// 数据库帮助类
	private DBHelper dbHelper;
    // Uri工具类
    private static final UriMatcher sUriMatcher;
    // 查询、更新条件
    private static final int EMPLOYEE = 1;
    private static final int EMPLOYEE_ID = 2;
    // 查询列集合
    private static HashMap<String, String> empProjectionMap;
    static {
    	// Uri匹配工具类
        sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        sUriMatcher.addURI(Employees.AUTHORITY, "employee", EMPLOYEE);
        sUriMatcher.addURI(Employees.AUTHORITY, "employee/#", EMPLOYEE_ID);
        // 实例化查询列集合
        empProjectionMap = new HashMap<String, String>();
        // 添加查询列
        empProjectionMap.put(Employee._ID, Employee._ID);
        empProjectionMap.put(Employee.NAME, Employee.NAME);
        empProjectionMap.put(Employee.GENDER, Employee.GENDER);
        empProjectionMap.put(Employee.AGE, Employee.AGE);
    }

	// 创建是调用
	public boolean onCreate() {
		// 实例化数据库帮助类
		dbHelper = new DBHelper(getContext());
		return true;
	}
	// 添加方法
	public Uri insert(Uri uri, ContentValues values) {
		// 获得数据库实例
		SQLiteDatabase db = dbHelper.getWritableDatabase();
		// 插入数据，返回行ID
		long rowId = db.insert(DBHelper.EMPLOYEES_TABLE_NAME, Employee.NAME, values);
		// 如果插入成功返回uri
        if (rowId > 0) {
            Uri empUri = ContentUris.withAppendedId(Employee.CONTENT_URI, rowId);
            getContext().getContentResolver().notifyChange(empUri, null);
            return empUri;
        }
		return null;
	}
	// 删除方法
	public int delete(Uri uri, String selection, String[] selectionArgs) {
		// 获得数据库实例
		SQLiteDatabase db = dbHelper.getWritableDatabase();
	 	// 获得数据库实例
        int count;
        switch (sUriMatcher.match(uri)) {
        // 根据指定条件删除
        case EMPLOYEE:
            count = db.delete(DBHelper.EMPLOYEES_TABLE_NAME, selection, selectionArgs);
            break;
        // 根据指定条件和ID删除
        case EMPLOYEE_ID:
            String noteId = uri.getPathSegments().get(1);
            count = db.delete(DBHelper.EMPLOYEES_TABLE_NAME, Employee._ID + "=" + noteId
                    + (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""), selectionArgs);
            break;

        default:
            throw new IllegalArgumentException("错误的 URI " + uri);
        }
        getContext().getContentResolver().notifyChange(uri, null);
        return count;
	}

	// 获得类型
	public String getType(Uri uri) {
		return null;
	}

	// 查询方法
	public Cursor query(Uri uri, String[] projection, String selection,
			String[] selectionArgs, String sortOrder) {
		 SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
	        switch (sUriMatcher.match(uri)) {
	        // 查询所有
	        case EMPLOYEE:
	            qb.setTables(DBHelper.EMPLOYEES_TABLE_NAME);
	            qb.setProjectionMap(empProjectionMap);
	            break;
	        // 根据ID查询
	        case EMPLOYEE_ID:
	            qb.setTables(DBHelper.EMPLOYEES_TABLE_NAME);
	            qb.setProjectionMap(empProjectionMap);
	            qb.appendWhere(Employee._ID + "=" + uri.getPathSegments().get(1));
	            break;
	        default:
	            throw new IllegalArgumentException("Uri错误！ " + uri);
	        }

	        // 使用默认排序
	        String orderBy;
	        if (TextUtils.isEmpty(sortOrder)) {
	            orderBy = Employee.DEFAULT_SORT_ORDER;
	        } else {
	            orderBy = sortOrder;
	        }

	        // 获得数据库实例
	        SQLiteDatabase db = dbHelper.getReadableDatabase();
	        // 返回游标集合
	        Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, orderBy);
	        c.setNotificationUri(getContext().getContentResolver(), uri);
	        return c;
	}

	// 更新方法
	public int update(Uri uri, ContentValues values, String selection,
			String[] selectionArgs) {
    	// 获得数据库实例
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        int count;
        switch (sUriMatcher.match(uri)) {
        // 根据指定条件更新
        case EMPLOYEE:
            count = db.update(DBHelper.EMPLOYEES_TABLE_NAME, values, selection, selectionArgs);
            break;
        // 根据指定条件和ID更新
        case EMPLOYEE_ID:
            String noteId = uri.getPathSegments().get(1);
            count = db.update(DBHelper.EMPLOYEES_TABLE_NAME, values, Employee._ID + "=" + noteId
                    + (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""), selectionArgs);
            break;
        default:
            throw new IllegalArgumentException("错误的 URI " + uri);
        }
        getContext().getContentResolver().notifyChange(uri, null);
        return count;
	}

}