shendongshia
8/23/2018 - 9:33 AM
JDBC
package com.company;
public class StringEquals
{
public static void main(String[] args)
{
String str1 = "java";
String str2 = "java";
String str3 = new String("java");
String str4 = new String("java");
System.out.println(str1 == str2 + "\n");
System.out.println("str1.equals(str2) : " + str1.equals(str2) + "\n");
System.out.println(str3 == str4 + "\n");
System.out.println("str3.equals(str4) : " + str3.equals(str4) + "\n");
System.out.println(str1 == str3 + "\n");
System.out.println("str1.equals(str3) : " + str1.equals(str3) + "\n");
//str1和str2是放在字符串常量池中，也就栈内存中的，因此str1和str2指向的是同一个字符串"java",因此它们地址和内容都是一样的
//str3和str4是放在堆内存中的，它俩具有相同的内容，但是不具有相同的内存地址
//当然str1和str3更不是相同的内存地址，只是相同的内容而已
}
}
package com.company;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class SerializeUtil
{
public static byte[] serialize(Object object)
{
try
{
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
objectOutputStream.writeObject(object);
byte[] bytes = byteArrayOutputStream.toByteArray();
return bytes;
}
catch (Exception e)
{
System.out.println("seriralize" + e);
}
return null;
}
public static Object unSerialize(byte[] bytes)
{
try
{
ByteArrayInputStream byteArrayOutputStream = new ByteArrayInputStream(bytes);
ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayOutputStream);
return objectInputStream.readObject();
}
catch (Exception e)
{
System.out.println("unseriralize" + e);
}
return null;
}
}
//JDBC如何实现回滚~
1 public void transaction() throws SQLException {
2 Connection conn = null;
3 PreparedStatement st = null;
4 ResultSet rs = null;
5 Savepoint sp = null; //代表回滚点对象
6 try{
7 conn = JdbcUtils.getConnection();
8 conn.setAutoCommit(false); //开启事务，相当于start transaction命令
9
10 String sql1 = "update account set money=money-100 where name='a'";
11 st = conn.prepareStatement(sql1);
12 st.executeUpdate();
13
14 sp = conn.setSavepoint(); //在此处设置回滚点
15
16 int x = 1/0; //在此处模拟事务处理过程中出错
17
18 String sql2 = "update account set money=money+100 where name='b'";
19 st = conn.prepareStatement(sql2);
20 st.executeUpdate();
21
22 conn.commit(); //提交事务
23 }catch (Exception e) {
24 conn.rollback(sp); //回滚到指定的回滚点处
25 conn.commit(); //回滚之后再次提交事务保证回滚点之前的SQL能被执行
26
27 }finally{
28 JdbcUtils.release(conn, st, rs);
29 }
30 }package com.company;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import java.io.ByteArrayOutputStream;
import java.util.*;
public class Main
{
private JedisPool jedisPool;
public static void main(String[] args)
{
// write your code here
Jedis jedis = new Jedis("127.0.0.1", 6379);
jedis.flushAll();
System.out.println("RedisServiceStart:" + jedis.ping());
Person personXia = new Person(100, "xiazhendong");
Person personJin = new Person(25, "jinpengcheng");
jedis.set(String.valueOf(personXia.getId()).getBytes(), SerializeUtil.serialize(personXia));
jedis.set(String.valueOf(personJin.getId()).getBytes(), SerializeUtil.serialize(personJin));
System.out.println("_____________________________________________");
Set<String> keysSet = jedis.keys("*");
Iterator<String> iterator = keysSet.iterator();
while (iterator.hasNext())
{
String key = iterator.next();
System.out.println("jedis key type is " + jedis.type(key));
byte[] person = jedis.get(key.getBytes());
Person personResultl = (Person) SerializeUtil.unSerialize(person);
System.out.println("Person " + personResultl.getName() +"is :\n"+ personResultl);
}
jedis.lpush("siteList","Runoob");
jedis.lpush("siteList","Google");
jedis.lpush("siteList","Tabao");
List<String> siteList = jedis.lrange("siteList",0,jedis.llen("siteList"));
jedis.del("siteList");
jedis.set("siteTaobao","taobao");
jedis.set("siteJD","JD");
jedis.set("siteTmall","tmall");
jedis.hset("peoppe","name","mayun");
String name =jedis.hget("people","name");
List<String> mget = jedis.mget("siteTaobao","siteJD","siteTmall");
String[] stringArray= new String[4];
stringArray[0] = "xia";
stringArray[1] = "zhen";
stringArray[2] = "dong";
stringArray[3] = "caca";
jedis.mset(stringArray);
String[] keyArray = new String[2];
keyArray[0]="xia";
keyArray[1]="dong";
List<String> stringList = jedis.mget(keyArray);
Set<String> keys = jedis.keys("*");
Iterator<String> it = keys.iterator();
while(it.hasNext())
{
String key = it.next();
System.out.println("--------------"+key+"--------------\n");
System.out.println("jedis key ttl is "+jedis.ttl(key));
System.out.println("jedis key persist is "+jedis.persist(key));
System.out.println("jedis key type is "+jedis.type(key));
if(jedis.type(key).equals("hash"))
{
System.out.println("jedis value hash is "+jedis.hget(key,"name"));
}
else if(jedis.type(key).equals("list"))
{
System.out.println("jedis value list is "+jedis.lrange(key,0,jedis.llen(key)));
}
else if(jedis.type(key).equals("string"))
{
System.out.println("jedis value string is "+jedis.get(key));
}
System.out.println("jedis key delete is "+jedis.del(key));
System.out.println("jedis key exist is "+jedis.exists(key));
System.out.println("--------------"+key+"--------------\n");
}
}
}
package com.company;
import java.io.Serializable;
public class Person implements Serializable
{
private int id;
private String name;
public Person(int id,String name)
{
this.id = id;
this.name = name;
}
public int getId()
{
return this.id;
}
public String getName()
{
return this.name;
}
@Override
public String toString()
{
return "Person{" +
"id=" + id +
", name='" + name + '\'' +
'}';
}
}