Simple Log Service:Get started with Simple Log Service SDK for Java

Step 1: Initialize the client

All operations in this tutorial use a shared Client instance. The endpoint determines which region handles your requests.

import com.aliyun.openservices.log.Client;

public class SlsQuickStart {
    // Obtain credentials from environment variables
    static String accessId = System.getenv("ALIBABA_CLOUD_ACCESS_KEY_ID");
    static String accessKey = System.getenv("ALIBABA_CLOUD_ACCESS_KEY_SECRET");

    // SLS endpoint for China (Hangzhou). Replace with your region endpoint.
    static String host = "cn-hangzhou.log.aliyuncs.com";

    static Client client = new Client(host, accessId, accessKey);
}

Replace cn-hangzhou.log.aliyuncs.com with the endpoint for your region. The endpoint format is <region-id>.log.aliyuncs.com.

Step 2: Create a project

A project is the top-level resource container in SLS. All logstores, indexes, and dashboards belong to a project.

static String projectName = "aliyun-test-gs-project";

static void createProject() throws LogException, InterruptedException {
    String projectDescription = "project description";
    System.out.println("ready to create project");
    client.CreateProject(projectName, projectDescription);
    System.out.println(String.format("create project %s success", projectName));
    // Wait for the project to become fully available after creation
    TimeUnit.SECONDS.sleep(60 * 2);
}

The 2-minute wait accounts for the time required for the project to become fully available after creation. In production, use polling or retry logic instead of a fixed sleep.

Step 3: Create a logstore

A logstore is a unit within a project that collects, stores, and queries log data. Each logstore has a configurable retention period and shard count.

static String logstoreName = "aliyun-test-logstore";

static void createLogstore() throws LogException, InterruptedException {
    System.out.println("ready to create logstore");
    int ttlInDay = 3;     // Data retention period in days. Set to 3650 for permanent storage.
    int shardCount = 2;   // Number of shards for read/write throughput
    LogStore store = new LogStore(logstoreName, ttlInDay, shardCount);
    client.CreateLogStore(projectName, store);
    System.out.println(String.format("create logstore %s success", logstoreName));
    // Wait for the logstore to become available
    TimeUnit.SECONDS.sleep(60);
}

Step 4: Create an index

An index enables log search and analytics on a logstore. This example creates both a full-text index and field indexes for the dev and id fields.

static void createIndex() throws LogException, InterruptedException {
    System.out.println(String.format("ready to create index for %s", logstoreName));
    // Index configuration:
    // - Full-text index with standard tokenizers (comma, space, quotes, brackets, etc.)
    // - Field index on "dev" (text type) and "id" (long type)
    // - Case-insensitive, Chinese tokenization disabled, max text length 2048
    String logstoreIndex = "{\"line\": {\"token\": [\",\", \" \", \"'\", \"\\\"\", \";\", \"=\", \"(\", \")\", \"[\", \"]\", \"{\", \"}\", \"?\", \"@\", \"&\", \"<\", \">\", \"/\", \":\", \"\\n\", \"\\t\", \"\\r\"], \"caseSensitive\": false, \"chn\": false}, \"keys\": {\"dev\": {\"type\": \"text\", \"token\": [\",\", \" \", \"'\", \"\\\"\", \";\", \"=\", \"(\", \")\", \"[\", \"]\", \"{\", \"}\", \"?\", \"@\", \"&\", \"<\", \">\", \"/\", \":\", \"\\n\", \"\\t\", \"\\r\"], \"caseSensitive\": false, \"alias\": \"\", \"doc_value\": true, \"chn\": false}, \"id\": {\"type\": \"long\", \"alias\": \"\", \"doc_value\": true}}, \"log_reduce\": false, \"max_text_len\": 2048}";
    Index index = new Index();
    index.FromJsonString(logstoreIndex);
    client.CreateIndex(projectName, logstoreName, index);
    System.out.println(String.format("create index for %s success", logstoreName));
    // Wait for the index to become available
    TimeUnit.SECONDS.sleep(60);
}

The index JSON configures the following settings:

Step 5: Write log data

Write 100 sample log items to the logstore. Each log item contains an id and a dev field.

static void pushLogs() throws LogException, InterruptedException {
    System.out.println(String.format("ready to push logs for %s", logstoreName));
    List<LogItem> logGroup = new ArrayList<LogItem>();
    for (int i = 0; i < 100; ++i) {
        LogItem logItem = new LogItem();
        logItem.PushBack("id", String.valueOf(i));
        logItem.PushBack("dev", "test_push");
        logGroup.add(logItem);
    }
    client.PutLogs(projectName, logstoreName, "", logGroup, "");
    System.out.println(String.format("push logs for %s success", logstoreName));
    // Brief wait for logs to be indexed
    TimeUnit.SECONDS.sleep(5);
}

PutLogs is suitable for low-volume scenarios. For high-throughput or high-concurrency workloads, use Alibaba Cloud Log Java Producer, which provides batching, retry, and async sending.

Step 6: Query logs

Run an SQL query to retrieve logs from the logstore within a one-hour window.

static String query = "*| select * from " + logstoreName;

static void queryLogs() throws LogException {
    System.out.println(String.format("ready to query logs from %s", logstoreName));
    // Query the last hour. fromTime and toTime are UNIX timestamps in seconds.
    int fromTime = (int) (System.currentTimeMillis() / 1000 - 3600);
    int toTime = fromTime + 3600;
    GetLogsResponse getLogsResponse = client.GetLogs(projectName, logstoreName, fromTime, toTime, "", query);
    for (QueriedLog log : getLogsResponse.getLogs()) {
        for (LogContent mContent : log.mLogItem.mContents) {
            System.out.println(mContent.mKey + " : " + mContent.mValue);
        }
        System.out.println("********************");
    }
}

Complete code

The following example combines all previous steps into a single runnable program. Create a file named SlsQuickStart.java and paste the code below.

import com.aliyun.openservices.log.common.Index;
import com.aliyun.openservices.log.common.LogContent;
import com.aliyun.openservices.log.common.LogItem;
import com.aliyun.openservices.log.common.LogStore;
import com.aliyun.openservices.log.common.QueriedLog;
import com.aliyun.openservices.log.exception.LogException;
import com.aliyun.openservices.log.response.GetLogsResponse;
import com.aliyun.openservices.log.Client;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;

public class SlsQuickStart {
    // Obtain credentials from environment variables
    static String accessId = System.getenv("ALIBABA_CLOUD_ACCESS_KEY_ID");
    static String accessKey = System.getenv("ALIBABA_CLOUD_ACCESS_KEY_SECRET");

    // SLS endpoint for China (Hangzhou). Replace with your region endpoint.
    static String host = "cn-hangzhou.log.aliyuncs.com";

    static Client client = new Client(host, accessId, accessKey);

    static String projectName = "aliyun-test-gs-project";
    static String logstoreName = "aliyun-test-logstore";
    static String query = "*| select * from " + logstoreName;

    static void createProject() throws LogException, InterruptedException {
        String projectDescription = "project description";
        System.out.println("ready to create project");
        client.CreateProject(projectName, projectDescription);
        System.out.println(String.format("create project %s success", projectName));
        TimeUnit.SECONDS.sleep(60 * 2);
    }

    static void createLogstore() throws LogException, InterruptedException {
        System.out.println("ready to create logstore");
        int ttlInDay = 3;
        int shardCount = 2;
        LogStore store = new LogStore(logstoreName, ttlInDay, shardCount);
        client.CreateLogStore(projectName, store);
        System.out.println(String.format("create logstore %s success", logstoreName));
        TimeUnit.SECONDS.sleep(60);
    }

    static void createIndex() throws LogException, InterruptedException {
        System.out.println(String.format("ready to create index for %s", logstoreName));
        String logstoreIndex = "{\"line\": {\"token\": [\",\", \" \", \"'\", \"\\\"\", \";\", \"=\", \"(\", \")\", \"[\", \"]\", \"{\", \"}\", \"?\", \"@\", \"&\", \"<\", \">\", \"/\", \":\", \"\\n\", \"\\t\", \"\\r\"], \"caseSensitive\": false, \"chn\": false}, \"keys\": {\"dev\": {\"type\": \"text\", \"token\": [\",\", \" \", \"'\", \"\\\"\", \";\", \"=\", \"(\", \")\", \"[\", \"]\", \"{\", \"}\", \"?\", \"@\", \"&\", \"<\", \">\", \"/\", \":\", \"\\n\", \"\\t\", \"\\r\"], \"caseSensitive\": false, \"alias\": \"\", \"doc_value\": true, \"chn\": false}, \"id\": {\"type\": \"long\", \"alias\": \"\", \"doc_value\": true}}, \"log_reduce\": false, \"max_text_len\": 2048}";
        Index index = new Index();
        index.FromJsonString(logstoreIndex);
        client.CreateIndex(projectName, logstoreName, index);
        System.out.println(String.format("create index for %s success", logstoreName));
        TimeUnit.SECONDS.sleep(60);
    }

    static void pushLogs() throws LogException, InterruptedException {
        System.out.println(String.format("ready to push logs for %s", logstoreName));
        List<LogItem> logGroup = new ArrayList<LogItem>();
        for (int i = 0; i < 100; ++i) {
            LogItem logItem = new LogItem();
            logItem.PushBack("id", String.valueOf(i));
            logItem.PushBack("dev", "test_push");
            logGroup.add(logItem);
        }
        client.PutLogs(projectName, logstoreName, "", logGroup, "");
        System.out.println(String.format("push logs for %s success", logstoreName));
        TimeUnit.SECONDS.sleep(5);
    }

    static void queryLogs() throws LogException {
        System.out.println(String.format("ready to query logs from %s", logstoreName));
        int fromTime = (int) (System.currentTimeMillis() / 1000 - 3600);
        int toTime = fromTime + 3600;
        GetLogsResponse getLogsResponse = client.GetLogs(projectName, logstoreName, fromTime, toTime, "", query);
        for (QueriedLog log : getLogsResponse.getLogs()) {
            for (LogContent mContent : log.mLogItem.mContents) {
                System.out.println(mContent.mKey + " : " + mContent.mValue);
            }
            System.out.println("********************");
        }
    }

    public static void main(String[] args) throws LogException, InterruptedException {
        createProject();
        createLogstore();
        createIndex();
        pushLogs();
        queryLogs();
    }
}

Expected output

After you run SlsQuickStart.java, the console prints:

ready to create project
create project aliyun-test-gs-project success
ready to create logstore
create logstore aliyun-test-logstore success
ready to create index for aliyun-test-logstore
create index for aliyun-test-logstore success
ready to push logs for aliyun-test-logstore
push logs for aliyun-test-logstore success
ready to query logs from aliyun-test-logstore
dev : test_push
id : 0
********************
dev : test_push
id : 1
********************
dev : test_push
id : 2
********************
...

The actual query output may also include system metadata fields such as __line__, __topic__, and __time___0.

References

• SLS SDK for Java on GitHub

• Error codes

• Common Alibaba Cloud SDKs for SLS

• Simple Log Service CLI

• SLS SDK for Python on GitHub