guava

package com.bjsxt.others.guava;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import com.google.common.collect.ImmutableList;

/**
 * 只读设置
 * @author Administrator
 *
 */
public class Demo01 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        List<String> list =new ArrayList<String>();
        list.add("a");
        list.add("b");
        list.add("c");
        //对原有的list进行包装，相等于原有List的一个视图，快照，不够安全
        List<String> readList =Collections.unmodifiableList(list);
        //java.lang.UnsupportedOperationException
        //readList.add("d");
        list.add("d"); //改变原有List 视图也一起改变
        
        //对比 查看 初始化List guava对只读设置 安全可靠，并且相对简单
        List<String> immutableList =ImmutableList.of("a", "b", "c"); 
        immutableList.add("d");//java.lang.UnsupportedOperationException
        
    }

}

package com.bjsxt.others.guava;

import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.List;
import java.util.Set;

import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.base.Predicate;
import com.google.common.collect.Collections2;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;

/**
 * 函数式编程 :解耦
 * 1、Predicate 
 * 2、Function
 * 
 * 工具:Collections2.filter() 过滤器
 * Collections2.transfer() 转换
 * Functions.compose()组合式函数编程
 * @author Administrator
 *
 */
public class Demo02 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        //组合式函数编程
        //确保容器中的字符串长度不超过5，超过进行截取，后全部大写
        List<String> list =Lists.newArrayList("bjsxt","good","happiness");
        //确保容器中的字符串长度不超过5，超过进行截取
        Function<String,String> f1 =new Function<String,String>(){

            @Override
            public String apply(String input) {
                return input.length()>5?input.substring(0,5):input;
            }
            
        };
        //转成大写
        Function<String,String> f2 =new Function<String,String>(){

            @Override
            public String apply(String input) {
                return input.toUpperCase();
            }
            
        };
        
        //String =f2(f1(String))
        Function<String,String> f =Functions.compose(f1, f2);
        Collection<String> resultCol =Collections2.transform(list, f);
        
        for(String temp:resultCol){
            System.out.println(temp);
        }
        
        
    }
    /**
     * 转换
     */
    public static void test2(){
        //类型转换
        Set<Long> timeSet =Sets.newHashSet();
        timeSet.add(10000000L);
        timeSet.add(99999999999999999L);
        timeSet.add(2000000000L);
        
        Collection<String> timeStrCol =Collections2.transform(timeSet, new Function<Long,String>(){

            @Override
            public String apply(Long input) {
                return new SimpleDateFormat("yyyy-MM-dd").format(input);
            }});
    
        for(String temp:timeStrCol){
            System.out.println(temp);
        }

    }
    /**
     * 过滤器
     */
    public static void test1(){
        //创建List 静态初始化
        List<String> list =Lists.newArrayList("moom","son","dad","bjsxt","refer");
        //找出回文 palindrome  backwords  mirror words
        //匿名内部类对象: 匿名内部类，同时创建类对象
        Collection<String> palindromeList =Collections2.filter(list, new Predicate<String>(){
    
            @Override
            public boolean apply(String input) {
                //业务逻辑
                return new StringBuilder(input).reverse().toString().equals(input);
            }
            
        });
        
        for(String temp:palindromeList){
            System.out.println(temp);
        }
    }
    
}

 

 

package com.bjsxt.others.guava;

import java.util.Set;


import com.google.common.base.Preconditions;
import com.google.common.collect.Constraint;
import com.google.common.collect.Constraints;
import com.google.common.collect.Sets;

/**
 * 加入约束条件:非空、长度验证
 * Constraint
 * Preconditions
 * Constraints
 * @author Administrator
 *
 */
public class Demo03 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Set<String> sets =Sets.newHashSet();
        //创建约束
        Constraint<String> constraint =new Constraint<String>(){

            @Override
            public String checkElement(String element) {
                //非空验证
                Preconditions.checkNotNull(element);
                //长度验证 5-20为字符串
                Preconditions.checkArgument(element.length()>=5 && element.length()<=20);
                                
                return element;
            }
            
        };
        
        Set<String> cs =Constraints.constrainedSet(sets, constraint);
        //cs.add(null); //java.lang.NullPointerException
    //    cs.add("good"); //java.lang.IllegalArgumentException
        cs.add("bjsxt");
        
        for(String str:cs){
            System.out.println(str);
        }
                
        
    }

}

package com.bjsxt.others.guava;

import java.util.Set;

import com.google.common.collect.Sets;
import com.google.common.collect.Sets.SetView;

/**
 * 集合的操作:交集、差集、并集
 * Sets.intersection()
 * Sets.difference()
 * Sets.union();
 * @author Administrator
 *
 */
public class Demo04 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Set<Integer> sets =Sets.newHashSet(1,2,3,4,5,6);
        Set<Integer> sets2 =Sets.newHashSet(3,4,5,6,7,8,9);
        
        //交集
        System.out.println("交集为:");
        SetView<Integer> intersection =Sets.intersection(sets, sets2);
        for(Integer temp:intersection){
            System.out.println(temp);
        }
        //差集
        System.out.println("差集为:");
        SetView<Integer> diff =Sets.difference(sets, sets2);
        for(Integer temp:diff){
            System.out.println(temp);
        }
        //并集
        System.out.println("并集为:");
        SetView<Integer> union =Sets.union(sets, sets2);
        for(Integer temp:union){
            System.out.println(temp);
        }
        
    }

}

 

package com.bjsxt.others.guava;

import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;

/**
 * HashMap 键唯一，值可以重复
 * BiMap:双向Map(Bidirectional Map ) 键与值都不能重复(unique -valued map)
 * @author Administrator
 *
 */
public class Demo07 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        BiMap<String,String> bimap=HashBiMap.create();
        bimap.put("bjsxt", "bjsxt@sina.com");
        bimap.put("good","good@qq.com");
        //通过邮箱找用户
        String user =bimap.inverse().get("good@qq.com");
        System.out.println(user);
        System.out.println(bimap.inverse().inverse()==bimap);
        
    }

}

 

 

package com.bjsxt.others.guava;

import java.util.Map;
import java.util.Set;

import com.google.common.collect.HashBasedTable;
import com.google.common.collect.Table;
import com.google.common.collect.Table.Cell;
import com.google.common.collect.Tables;

/**
 * 双键的Map -->Table -->rowKey+columnKey+value
 * 1、方法
 *  所有的行数据:cellSet()
 *  所有的学生: rowKeySet()
 *  所有的课程:columnKeySet()
 *  所有的成绩: values()
 *  学生对应的课程: rowMap() +get(学生)
 *                  row(学生)
 *  课程对应的学生: columnMap +get(课程)
 *                  column(课程)
 * @author Administrator
 *
 */
public class Demo08 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Table<String,String,Integer> tables=HashBasedTable.create();
        //测试数据
        tables.put("a", "javase", 80);
        tables.put("b", "javase", 90);
        tables.put("a", "oracle", 100);
        tables.put("c", "oracle", 95);
        
        //所有的行数据
        Set<Cell<String,String,Integer>> cells =tables.cellSet();
        for(Cell<String,String,Integer> temp:cells){
            System.out.println(temp.getRowKey()+"-->"+temp.getColumnKey()+"-->"+temp.getValue());
        }
        
        System.out.println("==========学生查看成绩==============");
        System.out.print("学生\t");
        //所有的课程
        Set<String> cours =tables.columnKeySet();
        for(String t:cours){
            System.out.print(t+"\t");
        }
        System.out.println();
        //所有的学生
        Set<String> stus =tables.rowKeySet();
        for(String stu:stus){
            System.out.print(stu+"\t");
            Map<String,Integer> scores =tables.row(stu);
            for(String c:cours){
                System.out.print(scores.get(c)+"\t");
            }
            System.out.println();
        }
        
        System.out.println("==========课程查看成绩==============");
        System.out.print("课程\t");
        //所有的学生
        Set<String> stuSet =tables.rowKeySet();
        for(String t:stuSet){
            System.out.print(t+"\t");
        }
        System.out.println();
        //所有的课程
        Set<String> courSet =tables.columnKeySet();
        for(String c:courSet){
            System.out.print(c+"\t");
            Map<String,Integer> scores =tables.column(c);
            for(String s:stuSet){
                System.out.print(scores.get(s)+"\t");
            }
            System.out.println();
        }
        System.out.println("===========转换===========");
        Table<String,String,Integer> tables2 =Tables.transpose(tables);
        //所有的行数据
        Set<Cell<String,String,Integer>> cells2 =tables2.cellSet();
        for(Cell<String,String,Integer> temp:cells2){
            System.out.println(temp.getRowKey()+"-->"+temp.getColumnKey()+"-->"+temp.getValue());
        }
        
    }

}