Febs

Febs is a common libraries in fluent API. Most api is like javascript.

• How to use
• Asynchronous in ThreadPool
• Asynchronous in Promise
• Network transfer in Fetch
• Utilities

How to use

maven config.

<dependency>
    <groupId>cn.brainpoint</groupId>
    <artifactId>febs</artifactId>
    <version>0.1.3</version>
</dependency>

import cn.brainpoint.febs;

//
// It will execute asynchronously after call `execute()`
//
PromiseFuture future = Febs.Net.fetch("https://xxx")
                            // get response status code.
                            .then(res->{
                                // code.
                                System.out.print(res.statusCode);
                                // message.
                                System.out.print(res.statusMsg);
                                
                                // get text content.
                                return res.text();
                            })
                            .then(content->{
                        
                            })
                            .execute();


//
// Can use `future.get()` to get result in synchronize.
//
String result = (String) future.get();

config

It can initial with thread pool config. Thread pool will affect performance of promise.

// Initial with thread pool config.
Febs.init(new Febs.ThreadPoolCfg(
                        2, 
                        4, 
                        20000, 
                        new LinkedBlockingQueue<>(),
                        new ThreadPoolExecutor.AbortPolicy())
         );

Asynchronous in ThreadPool

Use getExecutorService api to get a asynchronous work item.

try {
    Future<Object> future 
                    = Febs.getExecutorService.submit(()->{
                        // do anything in this thread.
                        return "any";
                    });
    Object result = future.get();
} catch (ExecutionException e) {
    e.printStackTrace();
} catch (InterruptedException e) {
    e.printStackTrace();
} catch (Exception e) {
    e.printStackTrace();
}

Asynchronous in Promise

Febs promise like javascript promise api, use chain list way to do asynchronous work.

• .then: same as js-es6 promise.then chain.
• .fail: same as js-es6 promise.catch chain.
• .finish: same as js promise.finally chain.
• .execute: It must be call to activate promise in Febs promise.

Base scene

/**
 * Make a promise object.
 */
Promise promise = new Promise((IResolve resolve, IReject reject)-> { 

                                // call this set status to 'fulfilled'
                                resolve.execute(retVal); 

                                // call this set status to 'rejected'
                                reject.execute(new Exception(""));
                            });

/**
 * chain.
 */
PromiseFuture = promise.then(res->{  })
                       .then(()->{ return 1; })
                       .then(res1->{  })
                       .fail(e->{  })  // same as javascript catch()
                       .finish(()->{}) // same as javascript finally()
                       .execute();  // activate promise.

/**
 * Block until promise finish, if you want to wait.
 */
PromiseFuture.get();

return another promise object in chain.

promise.then(res->{
            // this nest promise cannot call execute().
            return new Promise((resolve, reject)->{
                ...
            });
        })
        .then(res->{
        })
        .execute();

all

/**
 * Promise object array.
 * !Warning: All promise object cannot call execute() funciton.
 */
Promise[] promiseArr = {...};

/**
 * execute all promise object.
 */
Promise.all(promiseArr)
       .then(res->{
            // all promise done.
        })
        .fail(e->{
            // if some promise rejected.
        })
       .execute();

template

The then and fail chain can return a object to next chain. The data type of return value is unkonw, we can use template to spacify a data type.

e.g.

// Spacify a data type.
Promise<Integer> promise = new Promise<Integer>((IResolve<Integer> resolve, IReject reject)-> { 
                                resolve.execute(2); 
                            });

// use the data type.
promise.then((Integer res)->{ 
            // ...
        })
       .execute();  // execute promise.

Uncaught Exception Handler

Some promise object will catch exception use this method, if it have't call .fail()

Promise.setUncaughtExceptionHandler(e->{
  // handle error.
});

Network transfer in Fetch

The network transfer in fetch style

Get text content.

import cn.brainpoint.febs;

Febs.Net.fetch("https://xxxx")
        // get text content.
        .then(res->{ return res.text(); })
        // print content.
        .then(res->{
            System.out.print(res);
        })
        // If exception cause.
        .fail((e)->{
            System.err.print(e.getMessage());
        })
        .execute();

Get binary content.

import cn.brainpoint.febs;

Febs.Net.fetch("https://xxxx")
        // get blob content.
        .then(res->{ return res.blob(); })
        // print content.
        .then((res)->{
            BufferedReader in = (BufferedReader)res;
            char buf[] = new char[1024];

            while (in.read(buf, 0, buf.length) != -1) {
                System.out.printf("%s",  Arrays.toString(buf));
                Arrays.fill(buf, '\0');
            }

            // important to call close().
            in.close();
        })
        // If exception cause.
        .fail((e)->{
            System.err.print(e.getMessage());
        })
        .execute();

IMPORTANT: close BufferedReader after read blob.

Get response headers.

import cn.brainpoint.febs;

Febs.Net.fetch("https://xxxx")
        // get response status code.
        .then(res->{
            // code.
            System.out.print(res.statusCode);
            // message.
            System.out.print(res.statusMsg);
            
            return res;
        })
        // get response headers.
        .then(res->{
            Set<String> keySet = res.headers.keySet();
            Iterator<String> it1 = keySet.iterator();
            while(it1.hasNext()){
                String Key = it1.next();
                System.out.print("header: " + Key);
                List<String> values = res.headers.get(Key);
                System.out.print(values);
            }
        })
        // If exception cause.
        .fail((e)->{
            System.err.print(e.getMessage());
        })
        .execute();

Set request parameter

import cn.brainpoint.febs;

Febs.Net.fetch(new Requset(
                    url,
                    body,
                    method,
                    headers,
                    timeout,
                ))
        // get blob content.
        .then(res->{ return res.blob(); })
        .execute();

SSL trust manager

import cn.brainpoint.febs;

/**
 * set the trust manager.<br>
 * The default trust manager is trust all site.
 * 
 * @param trustManger the trust manager object.
 */
Febs.Net.setDefaultTrustManger(X509TrustManager trustManager);

Utilities

sleep

Use sleep API to schedule tasks.

import cn.brainpoint.febs;

Febs.Utils.sleep(1000)
        .then(()->{
            System.out.print("after 1000ms.");
        })
        .execute();


Febs.Utils.sleep(1000)
        .then(res->{
            System.out.print("after 1000ms.");
            return Febs.Utils.sleep(2000);
        })
        .then(res->{
            System.out.print("after 2000ms.");
        })
        .execute();