guava 集合在实体类中的应用示例
实体基类BaseEntity
package com.mytest;
import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;
public class BaseEntity {
private Long id;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
/**
* 覆盖toString方法，目的显示所有JavaBean的属性值，省略写很多的getXxx的方法
*/
public String toString() {
return ToStringBuilder.reflectionToString(this,
ToStringStyle.MULTI_LINE_STYLE);
}
}
实体类Person
package com.mytest;
public class Person extends BaseEntity{
private String name;
private String gender;
private int age;
private double weight;
public Person(Long id, String name, String gender, int age, double weight) {
super();
this.setId(id);
this.name = name;
this.gender = gender;
this.age = age;
this.weight = weight;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public double getWeight() {
return weight;
}
public void setWeight(double weight) {
this.weight = weight;
}
}
Example
package com.mytest;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.base.Function;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Ordering;
public class Example {
public static Logger logger = LoggerFactory.getLogger(Example.class);
public static void main(String[] args) {
List<Person> list = Lists.newArrayList();
list.add(new Person(4L,"jason", "male", 16, 120.50));
list.add(new Person(1L,"tom", "male", 48, 163.50));
list.add(new Person(3L,"john", "male", 33, 105));
list.add(new Person(2L,"rose", "female", 26, 90));
logger.debug(list.toString());
//获取ids
List<Long> ids = entityIds(list); //entityIds方法
logger.debug("---------------ids-------------------");
logger.debug(ids.toString());
logger.debug("---------------maps-------------------");
//获取map
Map<Long, Person> maps = entityMaps(list); //entityMaps方法
Set<Long> keys = maps.keySet();
for (Long id : keys) {
logger.debug("key: " + id + " value: " + maps.get(id));
}
}
/**
* 获取表记录集合的Id集合
* @param list
* @return
*/
public static<T extends BaseEntity> List<Long> entityIds(List<T> list){
List<Long> ids = Lists.transform(list, new Function<T, Long>(){
public Long apply(T entity){
return entity.getId();
}
});
return ids;
}
/**
* 根据实体记录，输出Map<Long id,K extend BaseEntity>集合
* @param list
* @return
*/
public static<V extends BaseEntity> Map<Long,V> entityMaps(List<V> list){
Map<Long,V> maps = Maps.uniqueIndex(list.iterator(), new Function<V, Long>() {
@Override
public Long apply(V entity) {
return entity.getId();
}
});
return maps;
}
}
entityIds方法
/**
* 获取表记录集合的Id集合
* @param list
* @return
*/
public static<T extends BaseEntity> List<Long> entityIds(List<T> list){
List<Long> ids = Lists.transform(list, new Function<T, Long>(){
public Long apply(T entity){
return entity.getId();
}
});
return ids;
}
entityMaps方法
/**
* 根据实体记录，输出Map<Long id,K extend BaseEntity>集合
* @param list
* @return
*/
public static<V extends BaseEntity> Map<Long,V> entityMaps(List<V> list){
Map<Long,V> maps = Maps.uniqueIndex(list.iterator(), new Function<V, Long>() {
@Override
public Long apply(V entity) {
return entity.getId();
}
});
return maps;
}
引入包，可参考pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.gzdfbz</groupId> <artifactId>mytest</artifactId> <version>0.0.1-SNAPSHOT</version> <dependencies> <dependency> <groupId>com.google.guava</groupId> <artifactId>guava</artifactId> <version>18.0</version> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.3.2</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.7.7</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-log4j12</artifactId> <version>1.7.7</version> </dependency> <dependency> <groupId>joda-time</groupId> <artifactId>joda-time</artifactId> <version>2.3</version> </dependency> </dependencies> </project>
log4j参考：
# log4j.rootLogger=DEBUG,console log4j.additivity.org.apache=true # log4j.appender.console=org.apache.log4j.ConsoleAppender log4j.appender.console.Threshold=DEBUG log4j.appender.console.ImmediateFlush=true log4j.appender.console.Target=System.err log4j.appender.console.layout=org.apache.log4j.PatternLayout #log4j.appender.console.layout.ConversionPattern=[%-5p] %d(%r) --> [%t] %l: %m %x %n log4j.appender.console.layout.ConversionPattern=%l: %m %x %n log4j.appender.com.mytest = debug