Translate java-api.en.md (#1126)

docs/content/user-manual/elasticjob-lite/usage/job-api/java-api.en.md

@@ -4,4 +4,67 @@ weight = 2
 chapter = true
 +++
 
-TODO
+## Job configuration
+
+ElasticJob-Lite uses the builder mode to create job configuration objects.
+The code example is as follows:
+
+```java
+    JobConfiguration jobConfig = JobConfiguration.newBuilder("myJob", 3).cron("0/5 * * * * ?").shardingItemParameters("0=Beijing,1=Shanghai,2=Guangzhou").build();
+```
+
+## Job start
+
+ElasticJob-Lite scheduler is divided into two types: timed scheduling and one-time scheduling.
+Each scheduler needs three parameters: registry configuration, job object (or job type), and job configuration when it starts.
+
+### Timed scheduling
+
+```java
+public class JobDemo {
+
+    public static void main(String[] args) {
+        // Class-based Scheduling Jobs
+        new ScheduleJobBootstrap(createRegistryCenter(), new MyJob(), createJobConfiguration()).schedule();
+        // Type-based Scheduling Jobs
+        new ScheduleJobBootstrap(createRegistryCenter(), "MY_TYPE", createJobConfiguration()).schedule();
+    }
+
+    private static CoordinatorRegistryCenter createRegistryCenter() {
+        CoordinatorRegistryCenter regCenter = new ZookeeperRegistryCenter(new ZookeeperConfiguration("zk_host:2181", "elastic-job-demo"));
+        regCenter.init();
+        return regCenter;
+    }
+
+    private static JobConfiguration createJobConfiguration() {
+        // Create job configuration
+        ...
+    }
+}
+```
+
+### One-time scheduling
+
+```java
+public class JobDemo {
+
+    public static void main(String[] args) {
+        OneOffJobBootstrap jobBootstrap = new OneOffJobBootstrap(createRegistryCenter(), new MyJob(), createJobConfiguration());
+        // One-time scheduling can be called multiple times
+        jobBootstrap.execute();
+        jobBootstrap.execute();
+        jobBootstrap.execute();
+    }
+
+    private static CoordinatorRegistryCenter createRegistryCenter() {
+        CoordinatorRegistryCenter regCenter = new ZookeeperRegistryCenter(new ZookeeperConfiguration("zk_host:2181", "elastic-job-demo"));
+        regCenter.init();
+        return regCenter;
+    }
+
+    private static JobConfiguration createJobConfiguration() {
+        // Create job configuration
+        ...
+    }
+}
+```