易采站长站为您分析Android内容提供者ContentProvider用法,结合实例形式较为详细的分析了内容提供者ContentProvider获取及解析数据的相关技巧,需要的朋友可以参考下
本文实例讲述了Android内容提供者ContentProvider用法。，具体如下：
PersonContentProvider内容提供者类
package com.ljq.db;
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.net.Uri;
import android.text.TextUtils;
/**
* 内容提供者
*
* 作用：统一数据访问方式，方便外部调用
*
* @author jiqinlin
*
*/
public class PersonContentProvider extends ContentProvider {
// 数据集的MIME类型字符串则应该以vnd.android.cursor.dir/开头
public static final String PERSONS_TYPE = "vnd.android.cursor.dir/person";
// 单一数据的MIME类型字符串应该以vnd.android.cursor.item/开头
public static final String PERSONS_ITEM_TYPE = "vnd.android.cursor.item/person";
public static final String AUTHORITY = "com.ljq.provider.personprovider";// 主机名
/* 自定义匹配码 */
public static final int PERSONS = 1;
/* 自定义匹配码 */
public static final int PERSON = 2;
public static final Uri PERSONS_URI = Uri.parse("content://" + AUTHORITY + "/person");
private DBOpenHelper dbOpenHelper = null;
// UriMatcher类用来匹配Uri，使用match()方法匹配路径时返回匹配码
private static final UriMatcher uriMatcher;
static {
// 常量UriMatcher.NO_MATCH表示不匹配任何路径的返回码
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
// 如果match()方法匹配content://com.ljq.provider.personprovider/person路径，返回匹配码为PERSONS
uriMatcher.addURI(AUTHORITY, "person", PERSONS);
// 如果match()方法匹配content://com.ljq.provider.personprovider/person/230路径，返回匹配码为PERSON
uriMatcher.addURI(AUTHORITY, "person/#", PERSON);
}
@Override
public boolean onCreate() {
dbOpenHelper = new DBOpenHelper(this.getContext());
return true;
}
@Override
public Uri insert(Uri uri, ContentValues values){
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
long id = 0;
switch (uriMatcher.match(uri)) {
case PERSONS:
id = db.insert("person", "name", values);// 返回的是记录的行号，主键为int，实际上就是主键值
return ContentUris.withAppendedId(uri, id);
case PERSON:
id = db.insert("person", "name", values);
String path = uri.toString();
return Uri.parse(path.substring(0, path.lastIndexOf("/"))+id); // 替换掉id
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
int count = 0;
switch (uriMatcher.match(uri)) {
case PERSONS:
count = db.delete("person", selection, selectionArgs);
break;
case PERSON:
// 下面的方法用于从URI中解析出id，对这样的路径content://com.ljq.provider.personprovider/person/10
// 进行解析，返回值为10
long personid = ContentUris.parseId(uri);
String where = "id=" + personid;// 删除指定id的记录
where += !TextUtils.isEmpty(selection) ? " and (" + selection + ")" : "";// 把其它条件附加上
count = db.delete("person", where, selectionArgs);
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
db.close();
return count;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
int count = 0;
switch (uriMatcher.match(uri)) {
case PERSONS:
count = db.update("person", values, selection, selectionArgs);
break;
case PERSON:
// 下面的方法用于从URI中解析出id，对这样的路径content://com.ljq.provider.personprovider/person/10
// 进行解析，返回值为10
long personid = ContentUris.parseId(uri);
String where = "id=" + personid;// 获取指定id的记录
where += !TextUtils.isEmpty(selection) ? " and (" + selection + ")" : "";// 把其它条件附加上
count = db.update("person", values, where, selectionArgs);
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
db.close();
return count;
}
@Override
public String getType(Uri uri) {
switch (uriMatcher.match(uri)) {
case PERSONS:
return PERSONS_TYPE;
case PERSON:
return PERSONS_ITEM_TYPE;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
switch (uriMatcher.match(uri)) {
case PERSONS:
return db.query("person", projection, selection, selectionArgs, null, null, sortOrder);
case PERSON:
// 下面的方法用于从URI中解析出id，对这样的路径content://com.ljq.provider.personprovider/person/10
// 进行解析，返回值为10
long personid = ContentUris.parseId(uri);
String where = "id=" + personid;// 获取指定id的记录
where += !TextUtils.isEmpty(selection) ? " and (" + selection + ")" : "";// 把其它条件附加上
return db.query("person", projection, where, selectionArgs, null, null, sortOrder);
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
}
}
