0
# HTTP Transport
1

2
The Google API Client provides HTTP transport implementations with SSL/TLS support and mutual TLS (mTLS) capabilities for secure communication with Google APIs.
3

4
## Core Imports
5

6
```java
7
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
8
import com.google.api.client.googleapis.apache.v2.GoogleApacheHttpTransport;
9
import com.google.api.client.googleapis.mtls.MtlsProvider;
10
import com.google.api.client.http.HttpTransport;
11
```
12

13
## Java.net HTTP Transport
14

15
### GoogleNetHttpTransport
16

17
Thread-safe factory for creating `NetHttpTransport` instances configured for Google APIs.
18

19
```java { .api }
20
public final class GoogleNetHttpTransport {
21
    public static NetHttpTransport newTrustedTransport() 
22
        throws GeneralSecurityException, IOException;
23
    
24
    @Beta
25
    public static NetHttpTransport newTrustedTransport(MtlsProvider mtlsProvider)
26
        throws GeneralSecurityException, IOException;
27
}
28
```
29

30
**Usage Example:**
31

32
```java
33
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
34
import com.google.api.client.http.HttpTransport;
35

36
// Create a trusted transport with Google's certificate trust store
37
HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
38

39
// Use with mTLS provider (Beta)
40
MtlsProvider mtlsProvider = // ... configure mTLS provider
41
HttpTransport mtlsTransport = GoogleNetHttpTransport.newTrustedTransport(mtlsProvider);
42
```
43

44
## Apache HTTP Transport
45

46
### GoogleApacheHttpTransport
47

48
Utilities for Google APIs based on `ApacheHttpTransport`.
49

50
```java { .api }
51
public final class GoogleApacheHttpTransport {
52
    public static ApacheHttpTransport newTrustedTransport()
53
        throws GeneralSecurityException, IOException;
54
    
55
    @Beta
56
    public static ApacheHttpTransport newTrustedTransport(MtlsProvider mtlsProvider)
57
        throws GeneralSecurityException, IOException;
58
}
59
```
60

61
**Usage Example:**
62

63
```java
64
import com.google.api.client.googleapis.apache.v2.GoogleApacheHttpTransport;
65
import com.google.api.client.http.apache.v2.ApacheHttpTransport;
66

67
// Create Apache-based transport
68
ApacheHttpTransport transport = GoogleApacheHttpTransport.newTrustedTransport();
69

70
// Use with custom mTLS configuration
71
MtlsProvider mtlsProvider = // ... configure mTLS provider  
72
ApacheHttpTransport mtlsTransport = GoogleApacheHttpTransport.newTrustedTransport(mtlsProvider);
73
```
74

75
## Mutual TLS (mTLS) Support
76

77
### MtlsProvider
78

79
Interface for providing mutual TLS configuration.
80

81
```java { .api }
82
@Beta
83
public interface MtlsProvider {
84
    boolean useMtlsClientCertificate();
85
    String getKeyStorePassword();
86
    KeyStore getKeyStore() throws IOException, GeneralSecurityException;
87
}
88
```
89

90
### MtlsUtils
91

92
Utility class for providing the default mutual TLS provider.
93

94
```java { .api }
95
@Beta
96
public class MtlsUtils {
97
    public static MtlsProvider getDefaultMtlsProvider();
98
}
99
```
100

101
**Usage Example:**
102

103
```java
104
import com.google.api.client.googleapis.mtls.MtlsUtils;
105
import com.google.api.client.googleapis.mtls.MtlsProvider;
106

107
// Get the default mTLS provider
108
MtlsProvider provider = MtlsUtils.getDefaultMtlsProvider();
109

110
// Check if mTLS should be used via the provider
111
if (provider.useMtlsClientCertificate()) {
112
    HttpTransport transport = GoogleNetHttpTransport.newTrustedTransport(provider);
113
}
114
```
115

116
### ContextAwareMetadataJson
117

118
Represents context-aware metadata for mTLS configuration.
119

120
```java { .api }
121
public class ContextAwareMetadataJson extends GenericJson {
122
    public List<LibraryInfo> getLibs();
123
    public void setLibs(List<LibraryInfo> libs);
124
    
125
    public static class LibraryInfo extends GenericJson {
126
        public String getName();
127
        public void setName(String name);
128
        public String getVersion(); 
129
        public void setVersion(String version);
130
    }
131
}
132
```
133

134
## Method Override Support
135

136
### MethodOverride
137

138
HTTP request interceptor for overriding HTTP methods using the `X-HTTP-Method-Override` header.
139

140
```java { .api }
141
public final class MethodOverride implements HttpRequestInitializer, HttpExecuteInterceptor {
142
    public static final String HEADER = "X-HTTP-Method-Override";
143
    
144
    public MethodOverride();
145
    
146
    public void initialize(HttpRequest request) throws IOException;
147
    public void intercept(HttpRequest request) throws IOException;
148
    
149
    public static final class Builder {
150
        public MethodOverride build();
151
        public boolean getOverrideAllMethods();
152
        public Builder setOverrideAllMethods(boolean overrideAllMethods);
153
    }
154
}
155
```
156

157
**Usage Example:**
158

159
```java
160
import com.google.api.client.googleapis.MethodOverride;
161
import com.google.api.client.http.HttpRequestInitializer;
162

163
// Create method override interceptor
164
MethodOverride methodOverride = new MethodOverride();
165

166
// Or with builder for custom configuration
167
MethodOverride customOverride = new MethodOverride.Builder()
168
    .setOverrideAllMethods(true)
169
    .build();
170

171
// Use as request initializer
172
HttpRequestInitializer requestInitializer = methodOverride;
173
```
174

175
## Types
176

177
### HttpTransport
178

179
Base interface for HTTP transport implementations (from google-http-client library).
180

181
### NetHttpTransport
182

183
Java.net-based HTTP transport implementation.
184

185
### ApacheHttpTransport  
186

187
Apache HttpClient-based HTTP transport implementation.
188

189
### KeyStore
190

191
Java security KeyStore for certificate management.
192

193
### GeneralSecurityException
194

195
Exception thrown for general security-related errors.
196

197
### IOException
198

199
Exception thrown for I/O-related errors.