JarCastingGood Programmers need Good Toolkits
How to write Java code more simply and efficiently?
You need have a set of tools are really suitable for you.
1. devtools-lang
For writing less code, there are many useful codes waiting for you to explore.
Maven
<dependency>
<groupId>com.github.paganini2008</groupId>
<artifactId>devtools-lang</artifactId>
<version>${devtools.version}</version>
</dependency>
2. devtools-objectpool
Contains object pool and jdbc connection pool. No extra functions.
Java Code
1. Object Pool
public static class Resource {
private final int id;
public Resource(int id) {
this.id = id;
}
public String doSomething(int i) {
return ThreadUtils.currentThreadName() + " do something: " + i;
}
public String toString() {
return "ID: " + id;
}
}
public static class ResourceFactory implements ObjectFactory {
private static final AtomicInteger seq = new AtomicInteger(0);
public Object createObject() throws Exception {
return new Resource(seq.incrementAndGet());
}
public void destroyObject(Object o) throws Exception {
System.out.println("Destory: " + o);
}
}
public static void main(String[] args) throws Exception {
GenericObjectPool objectPool = new GenericObjectPool(new ResourceFactory());
objectPool.setMaxPoolSize(10);
objectPool.setMaxIdleSize(3);
Executor executor = Executors.newFixedThreadPool(10);
AtomicInteger counter = new AtomicInteger();
for (final int i : Sequence.forEach(0, 10000)) {
executor.execute(() -> {
counter.incrementAndGet();
Resource resource = null;
try {
resource = (Resource) objectPool.borrowObject();
ThreadUtils.randomSleep(1000L);
System.out.println(resource.doSomething(i) + " :: busySize: " + objectPool.getBusySize() + ", idleSize: "
+ objectPool.getIdleSize());
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
objectPool.givebackObject(resource);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
System.in.read();
System.out.println(counter);
objectPool.close();
ExecutorUtils.gracefulShutdown(executor, 60000);
System.out.println("Done.");
}
2. DataSource
public static void main(String[] args) throws Exception {
GenericDataSource dataSource = new GenericDataSource();
dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
dataSource.setJdbcUrl(
"jdbc:mysql://localhost:3306/test?userUnicode=true&characterEncoding=UTF8&useSSL=false&serverTimezone=UTC&autoReconnect=true&zeroDateTimeBehavior=convertToNull");
dataSource.setUser("your name");
dataSource.setPassword("your password");
Executor executor = Executors.newFixedThreadPool(10);
for (final int i : Sequence.forEach(0, 10000)) {
executor.execute(() -> {
Connection connection = null;
Tuple tuple = null;
try {
connection = dataSource.getConnection();
tuple = JdbcUtils.fetchOne(connection, "select * from mec_area where level=? limit 1",
new Object[] { RandomUtils.randomInt(1, 4) });
System.out.println(tuple);
} catch (SQLException e) {
e.printStackTrace();
} finally {
JdbcUtils.closeQuietly(connection);
}
});
}
System.in.read();
// Sql Query Summary
Map<String, QuerySpan> results = dataSource.getStatisticsResult("dd/MM/yyyy");
System.out.println(results);
dataSource.close();
ExecutorUtils.gracefulShutdown(executor, 60000);
System.out.println("TestDataSource.main()");
}
Maven
<dependency>
<groupId>com.github.paganini2008</groupId>
<artifactId>devtools-objectpool</artifactId>
<version>${devtools.version}</version>
</dependency>
3. devtools-beans-streaming
To operate Java Collection Framework like using sql query. Is it cool? That's LINQ in Java!
Java Code
/**
* <pre>
* select * from Product where created<= now() and salesman.name='Petter'
* </pre>
*/
public static void test1() {
Predicate<Product> predicate = Restrictions.lte("created", new Date());
predicate = predicate.and(Restrictions.eq("salesman.name", "Petter"));
Select.from(products).filter(predicate).list().forEach(product -> {
System.out.println(product);
});
}
/**
* <pre>
* select location,max(price) as maxPrice, min(price) as minPrice,avg(freight) as avgFreight,sum(sales) as sumSales from Product group by location
* </pre>
*/
public static void test2() {
Select.from(products).groupBy("location", String.class).setTransformer(new View<Product>() {
protected void setAttributes(Tuple tuple, Group<Product> group) {
tuple.set("maxPrice", group.max("price", Float.class));
tuple.set("minPrice", group.min("price", Float.class));
tuple.set("avgFreight", group.avg("freight"));
tuple.set("sumSales", group.sum("sales"));
}
}).list().forEach(tuple -> {
System.out.println(tuple);
});
}
/**
* <pre>
* select location,style,max(price) as maxPrice, min(price) as minPrice,avg(freight) as avgFreight,sum(sales) as sumSales from Product group by location,style having avg(freight) > 55
* </pre>
*/
public static void test3() {
Select.from(products).groupBy("location", String.class).groupBy("style", Product.Style.class).having(group -> {
return group.avg("freight").compareTo(BigDecimal.valueOf(55)) > 0;
}).setTransformer(new View<Product>() {
protected void setAttributes(Tuple tuple, Group<Product> group) {
tuple.set("maxPrice", group.max("price", Float.class));
tuple.set("minPrice", group.min("price", Float.class));
tuple.set("avgFreight", group.avg("freight"));
tuple.set("sumSales", group.sum("sales"));
}
}).list().forEach(tuple -> {
System.out.println(tuple);
});
}
/**
* <pre>
* select name,price from Product order by price desc limit 100
* </pre>
*/
public static void test4() {
Select.from(products).orderBy(Orders.descending("price", Float.class)).list(100).forEach(product -> {
System.out.println("Name: " + product.getName() + ", Price: " + product.getPrice());
});
}
Maven
<dependency>
<groupId>com.github.paganini2008</groupId>
<artifactId>devtools-beans-streaming</artifactId>
<version>${devtools.version}</version>
</dependency>
4. devtools-scheduler
'0 0/5 12,18 * * ?' What's this? Doesn't you think the cron expression is anti-humanistic? You may change another style.
Java Code
// */5 * * * * ?
public static CronExpression getCron1() {
return CronBuilder.everySecond(5);
}
// 0 26,29,33 * * * ?
public static CronExpression getCron2() {
return CronBuilder.minute(26).andMinute(29).andMinute(33);
}
// 0 15 12 * * ?
public static CronExpression getCron3() {
return CronBuilder.everyDay().hour(12).minute(15);
}
// 0 15 10 ? * MON-FRI
public static CronExpression getCron4() {
return CronBuilder.everyWeek().Mon().toFri().at(10, 15, 0);
}
// 0 10 23 ? * 6#3
public static CronExpression getCron5() {
return CronBuilder.everyMonth().week(3).Fri().at(23, 10);
}
// 0 10,20,30 12 ? 3,4 5L 2002-2005
public static CronExpression getCron6() {
return CronBuilder.year(2020).toYear(2025).Mar().andApr().lastWeek().Thur().hour(12).minute(10).andMinute(20).andMinute(30);
}
Maven
<dependency>
<groupId>com.github.paganini2008</groupId>
<artifactId>devtools-scheduler</artifactId>
<version>${devtools.version}</version>
</dependency>
5. devtools-db4j
As a lazy man, to use JDBC more easily.
Java Code
/**
* Insert, Update, Delete in a transaction
*
* @throws SQLException
*/
public static void testUpdateInTransaction() throws SQLException {
String driverClassName = "com.mysql.cj.jdbc.Driver";
String jdbcUrl = "jdbc:mysql://localhost:3306/test?userUnicode=true&characterEncoding=UTF8&useSSL=false&serverTimezone=UTC&autoReconnect=true&zeroDateTimeBehavior=convertToNull";
String user = "your_user";
String password = "your_password";
SqlPlus sqlPlus = new SqlPlus(driverClassName, jdbcUrl, user, password);
Transaction transaction = null;
try {
transaction = sqlPlus.beginTransaction(); // Open transaction
GeneratedKey generatedKey = GeneratedKey.forNames("id");
Point point = new Point();// Pojo
point.setUsername("tester-12");
point.setPoints(100);
point.setTag(5);
point.setDate(new Date());
int effectedRows = transaction.update(
"insert into tb_point (username,points,tag,last_modified) values ({username},{points},{tag},{date})",
new BeanPropertySqlParameter(point), generatedKey); // bean mapping
System.out.println("EffectedRows: " + effectedRows);
System.out.println("Added id: " + generatedKey.getKey());
Map<String, Object> parameterMap = new HashMap<String, Object>();
parameterMap.put("points", 10);
parameterMap.put("username", "tester-12");
effectedRows = transaction.update("update tb_point set points=points+{points} where username={username}",
new MapSqlParameter(parameterMap)); // Map mapping
System.out.println("EffectedRows: " + effectedRows);
effectedRows = transaction.update("delete from tb_point where username!={0}", new ArraySqlParameter("tester-12")); // Array
// mapping
System.out.println("EffectedRows: " + effectedRows);
transaction.commit();
} catch (SQLException e) {
transaction.rollback();
throw e;
} finally {
transaction.close(); // Transaction end
}
}
/**
* Query for List
*
* @throws SQLException
*/
public static void testQuery() throws SQLException {
String driverClassName = "com.mysql.cj.jdbc.Driver";
String jdbcUrl = "jdbc:mysql://localhost:3306/test?userUnicode=true&characterEncoding=UTF8&useSSL=false&serverTimezone=UTC&autoReconnect=true&zeroDateTimeBehavior=convertToNull";
String user = "your_user";
String password = "your_password";
SqlPlus sqlPlus = new SqlPlus(driverClassName, jdbcUrl, user, password);
List<Tuple> dataList = sqlPlus.queryForList("select * from tb_point", new Object[0]);
dataList.forEach(tuple -> {
System.out.println(tuple);
});
}
/**
* Pageable Query
*
* @throws SQLException
*/
public static void testPageableQuery() throws SQLException {
String driverClassName = "com.mysql.cj.jdbc.Driver";
String jdbcUrl = "jdbc:mysql://localhost:3306/test?userUnicode=true&characterEncoding=UTF8&useSSL=false&serverTimezone=UTC&autoReconnect=true&zeroDateTimeBehavior=convertToNull";
String user = "your_user";
String password = "your_password";
SqlPlus sqlPlus = new SqlPlus(driverClassName, jdbcUrl, user, password);
PageableQuery<Tuple> pageableQuery = sqlPlus.queryForPage("select * from tb_point where points>{0}", new Object[] { 10 });
for (PageResponse<Tuple> pageResponse : pageableQuery.forEach(1, 10)) {// Page start from 1
System.out.println("Page: " + pageResponse.getPageNumber());
pageResponse.getContent().forEach(tuple -> {
System.out.println(tuple); // Iterator each record
});
}
}
Maven
<dependency>
<groupId>com.github.paganini2008</groupId>
<artifactId>devtools-db4j</artifactId>
<version>${devtools.version}</version>
</dependency>
At last, you can also use all in your application:
<dependency>
<groupId>com.github.paganini2008</groupId>
<artifactId>devtools</artifactId>
<version>${devtools.version}</version>
<type>pom</type>
</dependency>