设置<元组>未正确添加值</tuple>

Question

我正在开发类似Redis的开源Memcache API：http://bit.ly/XVfpRX

任何人都可以帮我分析为什么此代码的String field和String value变量值不正确：

public Long hset(String key, String field, String value) {
    System.out.println("HSET key="+key+" field=" + field + " value="+value);
    try {
        boolean exist = exists(key);
        if(exist){
            Set<Tuple<String,String>> hash = (Set<Tuple<String,String>>) memget(key);
            Iterator<Tuple<String, String>> it = hash.iterator();
            while (it.hasNext()){
                Tuple<String, String> t = it.next();
                if (t.getFirst().equals(field)){
                    System.out.println("HSET Removing field=" + t.getFirst() + " value="+t.getSecond());
                    hash.remove(t);
                    hash.add(new Tuple<String, String>(field, value));
                }
            }
            memset(key, hash);
            return 0L;
        } else {
            Set<Tuple<String,String>> hash = new HashSet<Tuple<String,String>>();
            System.out.println("Adding new tuple key="+key+" field=" + field + " value="+value);
            hash.add(new Tuple<String, String>(field, value));
            memset(key, hash);  
            return 1L;
        }
    } catch(Exception e) { //  ClassCastException and NPE
        // What to do when CCE is encountered?
        Set<Tuple<String,String>> hash = new HashSet<Tuple<String,String>>();
        hash.add(new Tuple<String, String>(field, value));
        memset(key, hash);              
    } 
    return 1L;
}

以下是测试日志：

Start hset tests
HSET key=null field=null value=null
Adding new tuple key=null field=null value=null
MEMSET key=null value=[Tuple [first=null, second=null]]
HSET key=foo field=foo value=bar
Adding new tuple key=foo field=foo value=bar
MEMSET key=foo value=[Tuple [first=foo, second=bar]]
HSET key=foo field=bar value=foobar
MEMSET key=foo value=[Tuple [first=foo, second=bar]]
HSET key=user:1 field=uname value=foo
Adding new tuple key=user:1 field=uname value=foo
MEMSET key=user:1 value=[Tuple [first=uname, second=foo]]
HSET key=user:1 field=fname value=Bar
MEMSET key=user:1 value=[Tuple [first=uname, second=foo]]
HSET key=user:1 field=uname value=bar
HSET Removing field=uname value=foo
MEMSET key=user:1 value=[Tuple [first=uname, second=bar]]

还有实际的JUnit测试：

@Test
public void testHset() {
    System.out.println("Start hset tests");
    Long ret = lingo.hset(key, null, value);
    assertEquals(1L, ret.longValue());
    ret = lingo.hset("foo", "foo", "bar");
    assertEquals(1L, ret.longValue());
    ret = lingo.hset("foo", "bar", "foobar");
    assertEquals(0L, ret.longValue());

    ret = lingo.hset("user:1", "uname", "foo");
    assertEquals(1L, ret.longValue());
    ret = lingo.hset("user:1", "fname", "Bar");
    assertEquals(0L, ret.longValue());
    ret = lingo.hset("user:1", "uname", "bar");
    assertEquals(0L, ret.longValue());

    String username = lingo.hget("user:1", "uname");
    String firstname = lingo.hget("user:1", "fname");
    assertEquals("bar", username);
    assertEquals("Bar", firstname);
    System.out.println("End hset tests");
}

问题在于：

HSET key=foo field=bar value=foobar
MEMSET key=foo value=[Tuple [first=foo, second=bar]]

和此：

HSET key=user:1 field=fname value=Bar
MEMSET key=user:1 value=[Tuple [first=uname, second=foo]]

传播到memset的字段和值（这是GAE memcache put的键值包装方法）是错误的。

The Tuple code can be found here

更新（添加了hget方法）：

public String hget(String key, String field) {
    try {
        boolean exist = exists(key);
        if(exist){
            Set<Tuple<String,String>> hash = (Set<Tuple<String,String>>) memget(key);
            Iterator<Tuple<String, String>> it = hash.iterator();
            while (it.hasNext()){
                Tuple<String, String> t = it.next();
                if (t.getFirst().equals(field)){
                    return t.getSecond();
                }
            }
        } 
    } catch(Exception e) { //  ClassCastException and NPE
        // What to do when CCE is encountered?
    } 
    return "nil";
}

Answer 1

您是否写过Tuple课程？

我首先想到的是你没有正确覆盖equals和hashCode。 Joshua Bloch的Effective Java告诉你如何。