要解决"AWS Java SDK错误 - 对于IAM用户的withPermissionsBoundary"，您可以使用以下代码示例：

import com.amazonaws.services.identitymanagement.AmazonIdentityManagement;
import com.amazonaws.services.identitymanagement.AmazonIdentityManagementClientBuilder;
import com.amazonaws.services.identitymanagement.model.AttachUserPolicyRequest;
import com.amazonaws.services.identitymanagement.model.CreateUserRequest;
import com.amazonaws.services.identitymanagement.model.NoSuchEntityException;
import com.amazonaws.services.identitymanagement.model.PutUserPolicyRequest;
import com.amazonaws.services.identitymanagement.model.User;

public class IAMExample {
    public static void main(String[] args) {
        String userName = "your-iam-username";
        String policyArn = "arn:aws:iam::aws:policy/YourPolicyName";
        String permissionsBoundaryArn = "arn:aws:iam::123456789012:policy/YourPermissionsBoundaryPolicyName";

        AmazonIdentityManagement iamClient = AmazonIdentityManagementClientBuilder.defaultClient();

        try {
            // 创建IAM用户
            CreateUserRequest createUserRequest = new CreateUserRequest()
                    .withUserName(userName)
                    .withPermissionsBoundary(permissionsBoundaryArn);
            User user = iamClient.createUser(createUserRequest).getUser();

            // 绑定策略到IAM用户
            AttachUserPolicyRequest attachUserPolicyRequest = new AttachUserPolicyRequest()
                    .withUserName(userName)
                    .withPolicyArn(policyArn);
            iamClient.attachUserPolicy(attachUserPolicyRequest);

            // 更新IAM用户策略
            String policyName = "YourPolicyName";
            String policyDocument = "{\"Version\":\"2012-10-17\",\"Statement\":[{\"Effect\":\"Allow\",\"Action\":\"s3:GetObject\",\"Resource\":\"arn:aws:s3:::your-bucket-name/*\"}]}";
            PutUserPolicyRequest putUserPolicyRequest = new PutUserPolicyRequest()
                    .withUserName(userName)
                    .withPolicyName(policyName)
                    .withPolicyDocument(policyDocument);
            iamClient.putUserPolicy(putUserPolicyRequest);

            System.out.println("IAM用户创建成功！");
        } catch (NoSuchEntityException e) {
            System.err.println("找不到指定的权限边界策略或策略不存在！");
        }
    }
}

在上面的代码示例中，我们使用了AWS Java SDK的AmazonIdentityManagement客户端来执行以下操作：

1. 创建一个IAM用户，并将指定的权限边界策略应用到该用户上。
2. 将指定的策略（ARN）附加到IAM用户上。
3. 更新IAM用户的策略。

请替换代码示例中的占位符（如your-iam-username、arn:aws:iam::aws:policy/YourPolicyName、arn:aws:iam::123456789012:policy/YourPermissionsBoundaryPolicyName和arn:aws:s3:::your-bucket-name/*）为您自己的值。

确保您已正确配置AWS凭证，以便在运行代码时进行身份验证。