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Java DynamoDB 增加、删除、修改、查询

2019年05月17日  | 移动技术网IT编程  | 我要评论

准备jar包

<dependency>
    <groupid>com.amazonaws</groupid>
    <artifactid>aws-java-sdk-core</artifactid>
    <version>1.11.534</version>
</dependency>
<dependency>
    <groupid>com.amazonaws</groupid>
    <artifactid>aws-java-sdk-dynamodb</artifactid>
    <version>1.11.46</version>
</dependency>

准备对象：

//用户凭证
private static string awsaccesskeyid = "xxx";
private static string awssecretkey = "xxx";
//表名
private static string table_name = "xxx";
//用户凭证对象
private static awscredentialsprovider awscredentialsprovider = new awscredentialsprovider() {
　　public void refresh() {}
　　public awscredentials getcredentials() {return new basicawscredentials(awsaccesskeyid, awssecretkey);}
};
//表的相关对象
private static amazondynamodb amazondynamodbclient = null;
private static dynamodbmapper dbmapper = null;
private static table table = null;

数据库表映射对象：

@dynamodbtable(tablename = "xxx")
public class user {
    private string id = null;
    private string name = null;
    private string telephone = null;

    public user(string id, string name, string telephone) {
        super();
        this.id = id;
        this.name = name;
        this.telephone = telephone;
    }
　　//主键
    @dynamodbhashkey(attributename = "id")
    public string getid() {
        return id;
    }

    public void setid(string id) {
        this.id = id;
    }

    public user() {
    }
　　//配有索引 username-index
    @dynamodbattribute(attributename = "username")
    public string getname() {
        return name;
    }

    public void setname(string name) {
        this.name = name;
    }
　　//配有索引 telephone-index
    @dynamodbattribute(attributename = "telephone")
    public string gettelephone() {
        return telephone;
    }

    public void settelephone(string telephone) {
        this.telephone = telephone;
    }
}

初始化对象：

 

amazondynamodbclient =  amazondynamodbclientbuilder.standard().withcredentials(awscredentialsprovider).withregion(regions.ap_northeast_1).build();
dbmapper = new dynamodbmapper(amazondynamodbclient);
table = new  dynamodb(amazondynamodbclient).gettable(table_name);

根据id查询一条：

public static user getitembyid(string id) {
        return dbmapper.load(user.class, id);
    }

根据指定索引查询多条：

public static list<user> getitembykey(string key, string value) {
　　　　//取索引
        index index = table.getindex(key + "-index");
        hashmap<string, string> namemap = new hashmap<string, string>();
        namemap.put("#key", key);
        hashmap<string, object> valuemap = new hashmap<string, object>();
        valuemap.put(":value", value);
　　　　//创建筛选条件，以map的形式传入key和value，条件只能用 = 号，其他未考证
        queryspec queryspec = new queryspec().withkeyconditionexpression("#key = :value").withnamemap(namemap)
                .withvaluemap(valuemap);
        itemcollection<queryoutcome> items = index.query(queryspec);
        iterator<item> iterator = items.iterator();
        item item = null;
        list<user> users = new arraylist<user>();
        while (iterator.hasnext()) {
            item = iterator.next();
            dashbuttonusers.add(new dashbuttonuser(item.getstring("id"),item.getstring("username"),item.getstring("telephone"));
        }
        return users;
    }

根据指定条件扫描多条：

public static list<user> getitembytimerange(long starttime, long endtime) {
        map<string, attributevalue> expressionattributevalues = new hashmap<string, attributevalue>();
        expressionattributevalues.put(":starttime", new attributevalue().withn("" + starttime));
        expressionattributevalues.put(":endtime", new attributevalue().withn("" + endtime));
　　　　//筛选条件
        scanrequest scanrequest = new scanrequest().withtablename(table_name)
                .withfilterexpression("starttime >= :starttime and endtime <= :endtime")
                .withexpressionattributevalues(expressionattributevalues);
        scanresult result = amazondynamodbclient.scan(scanrequest);
        list<user> users = new arraylist<user>();
        for (map<string, attributevalue> item : result.getitems()) {
                dashbuttonusers.add(new dashbuttonuser(/* 略 */));
        }
        return users;
    }

根据id删除：

//删除一条
public static void deleteitembyid(string id) {
    dbmapper.delete(new dashbuttonuser(id, null, null, null, null, null, null));
    }
//删除多条
public static void deletebatch(list<user> ids) {
　　//ids[0] -->{"id":"xxx","telephone":null,"name":null}
    dbmapper.batchdelete(ids);
    }

添加、修改：

//添加、修改一条
public static void addorupdateoneitem(user user) {
        dbmapper.save(user);
    }
//添加、修改多条
public static list<failedbatch>  addorupdatebatch(list<user> users) {
        return dbmapper.batchsave(users);
    }

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