http断点续传简单实现（java)

/* l@GJcCufE  
**SiteFileFetch.java nm<VcCc  
*/ c$ib-
  
package NetFox; V^Z5i]zT  
import java.io.*; rM= :{   
import java.net.*; Lwi"K8.u  
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public class SiteFileFetch extends Thread { Rf`_q7fm  
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SiteInfoBean siteInfoBean = null; //文件信息Bean LRu*%3xx  
long[] nStartPos; //开始位置 yKj}l,i~8  
long[] nEndPos; //结束位置 +zche  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 %eofG]VM<  
long nFileLength; //文件长度 /Lr`Aka5  
boolean bFirst = true; //是否第一次取文件 *)w+xWmM3w  
boolean bStop = false; //停止标志 %Jh(5  
File tmpFile; //文件下载的临时信息 *Lz'<=DLoW  
DataOutputStream output; //输出到文件的输出流 8f~x\.  
w`8H=Hf  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） -V4{tIQY  
public SiteFileFetch(SiteInfoBean bean) throws IOException qVfn(rZ  
{ HM)D/CO,?  
siteInfoBean = bean; |z3!3?%R  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ,|yscp8  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ;Z0&sFm  
if(tmpFile.exists ()) O0'|\:my  
{ XTX/vbge3m  
bFirst = false; Z_bVCe{  
read_nPos(); AC <2.i_  
} U{ 0~&  
else B0yGr\KJ  
{ {~51h}>b#  
nStartPos = new long[bean.getNSplitter()]; L''VBY"?  
nEndPos = new long[bean.getNSplitter()]; -eV*I>G  
}
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} 3
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@ ^F{  
public void run() kb~ s,@p  
{ Oz\J+  
//获得文件长度 ,)\G<q yO6  
//分割文件 Ag:/iB]  
//实例FileSplitterFetch AX+]Z$  
//启动FileSplitterFetch线程 _Fj\0S"  
//等待子线程返回 n7ZJ< ~wl  
try{ %2D'NZS  
if(bFirst) ts[8;<YD  
{ I&15[:b=-  
nFileLength = getFileSize(); ,ynN801\m  
if(nFileLength == -1) lgVT~v{U`n  
{ }Tm+gJA  
System.err.println("File Length is not known!"); +K'YVB U}  
} (L4C1h_]9  
else if(nFileLength == -2) 34)l3UI~  
{ })@xWU6!  
System.err.println("File is not access!"); C<:wSS^@1  
} 0# 1~'e  
else P;y!Y/$C  
{ ^=-25%&^  
for(int i=0;i<nStartPos.length;i++) )2W7>
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{ -u~:Gd*l0  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ?S=y>b9R  
} dmkGIg}  
for(int i=0;i<nEndPos.length-1;i++) I31Nu{  
{ D?Ol)aj?  
nEndPos = nStartPos[i+1]; ?T%"Jgy8  
} @fo(#i&  
nEndPos[nEndPos.length-1] = nFileLength; wb#[&2
i  
} tD}{/`{_t  
} !Y UT*  
!T)_(}|6}  
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//启动子线程 K(MZ!>{  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; `_neYT  
for(int i=0;i<nStartPos.length;i++) G~&q  
{ dwvc;f-  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), vfc5M6Vm)<  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), H 9/m6F  
nStartPos,nEndPos,i); er 1zSTkg  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `3K."/N6c  
fileSplitterFetch.start(); IYptNR  
} UZiL NKc  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), <uoVGV5N  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 0.!vp?  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", UDkH'x$=  
nEndPos = " + nFileLength); +('xzW  
// fileSplitterFetch[nPos.length-1].start(); Xsb.xxK.  
s;Zi   
56C'<#  
//等待子线程结束 _8`S&[E?  
//int count = 0; P%w!4v~"  
//是否结束while循环 |,.1=|&u  
boolean breakWhile = false; ~|{e"!(}  
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while(!bStop) HCktgL:E=  
{ c0jTQMe4yl  
write_nPos(); J~
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Utility.sleep(500); ;6]ag< Q  
breakWhile = true; bS|h~B]rd  
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{}
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for(int i=0;i<nStartPos.length;i++) ed/ "OgA  
{ =y?Aeqq\fl  
if(!fileSplitterFetch.bDownOver) p*zTuB~e<  
{ @1k-h;`,  
breakWhile = false; A$P Oc<  
break; a(-t"OL\  
} 6]!Jo)BF  
} N^[MeG,8  
if(breakWhile) 5P
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break; Ho%%voJBS  
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_!vuDv%  
//count++; 9j;!4AJ1t  
//if(count>4) 4 ;6,h6a  
// siteStop(); &ML-\aSal  
} vvG*DGL)qL  
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System.err.println("文件下载结束！"); {>ghX_m|  
} FVOPC:}bj  
catch(Exception e){e.printStackTrace ();} aNICSxDN  
} \H PB{ ;  
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//获得文件长度 gZz5P
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public long getFileSize() mX@xV*  
{ *L<<S=g$2  
int nFileLength = -1; FYg{IKg  
try{ 77]Fp(uI  
URL url = new URL(siteInfoBean.getSSiteURL()); 6%c]{eTd9  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); a}k5[)et  
httpConnection.setRequestProperty("User-Agent","NetFox"); `- 9p)@'8k  
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int responseCode=httpConnection.getResponseCode(); HErG%v]nw  
if(responseCode>=400) d(D|rf,av  
{ |t58n{V.O  
processErrorCode(responseCode); cGg~+R2P  
return -2; //-2 represent access is error m$'ZiS5  
} -OgC.6  
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String sHeader; <5|:QLqy  
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for(int i=1;;i++) %:-2P  
{ A22'qgKm@  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); dP/1E6*m  
//Utility.log(in.readLine()); %wq;<'W  
sHeader=httpConnection.getHeaderFieldKey(i); `4|:8@,3{  
if(sHeader!=null) ^ -lWv  
{ .k5&C/jv  
if(sHeader.equals("Content-Length")) S]c&T`jx  
{ `y&2Bf  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); T' )l  
break; s%zdP  
} \-Q
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} NF*Z<$'%  
else .Ax]SNZ+:A  
break; FCt %of#  
} EHq?yj;  
} >\1j`/ :ZI  
catch(IOException e){e.printStackTrace ();} [@$t35t~  
catch(Exception e){e.printStackTrace ();} 1|7tq  
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Utility.log(nFileLength); WP?AQD  
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return nFileLength; EUuk%<q7C(  
} WQltUaF  
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//保存下载信息（文件指针位置） c"S{5xh0&  
private void write_nPos() ZcrFzi  
{ 3m/XT"D  
try{ /,^AG2]( f  
output = new DataOutputStream(new FileOutputStream(tmpFile)); k:`yxxYIh  
output.writeInt(nStartPos.length); .QM>^(o$Z  
for(int i=0;i<nStartPos.length;i++) }m.45n/  
{ GsNZr=;C  
// output.writeLong(nPos); .vtV2lq  
output.writeLong(fileSplitterFetch.nStartPos); Uf\U~wM<  
output.writeLong(fileSplitterFetch.nEndPos); $xq$  
} 9at_F'>R  
output.close(); I73=PfS:m  
} 2j-^F  
catch(IOException e){e.printStackTrace ();} T5+9#  
catch(Exception e){e.printStackTrace ();} w@hbY:Z9z  
} K\^S>
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//读取保存的下载信息（文件指针位置） 9 EV.![  
private void read_nPos() p2(Z(V7*  
{ L
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try{ LZ1)zoJ  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); _ v3VUm#  
int nCount = input.readInt(); Hus.Jfam  
nStartPos = new long[nCount]; Pbl#ieZM  
nEndPos = new long[nCount]; )&.Zxo;q=  
for(int i=0;i<nStartPos.length;i++) ;a~ e  
{ wp>L}!  
nStartPos = input.readLong(); (cm8x  
nEndPos = input.readLong(); 5/m}v'S%  
} Fz@9
@  
input.close(); %@Nu{?I  
} _'Hw`0}s  
catch(IOException e){e.printStackTrace ();} gH|:=vfYUR  
catch(Exception e){e.printStackTrace ();} iO{LsG*5Z  
} `E8D5'tt  
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private void processErrorCode(int nErrorCode) NWII?X#T}  
{ NbUbLzE  
System.err.println("Error Code : " + nErrorCode); x5eSPF1  
} "g&hsp+i"A  
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//停止文件下载 U,7}VdO  
public void siteStop() &ZI-#(P  
{ ;]^% 6B n  
bStop = true; L4or*C^3  
for(int i=0;i<nStartPos.length;i++) 80 ckh  
fileSplitterFetch.splitterStop(); ZP9x3MHe  
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Z^_gS&nDa~  
} (W+aeB0  
} q@vqhE4  
//负责部分文件的抓取 L"}tJM.d  
**FileSplitterFetch.java w/csLi.O  
*/ <"{VVyK  
package NetFox; D 3Tqk^5  
$+$4W\-=X  
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import java.io.*; ;2[),k  
import java.net.*; o2!wz8  
6o4Y]C2W{1  
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public class FileSplitterFetch extends Thread { k{D0
&
 
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 w>\_d  
String sURL; //File URL WaSZw0U}y  
long nStartPos; //File Snippet Start Position 06]"{2  
long nEndPos; //File Snippet End Position slAR<8  
int nThreadID; //Thread's ID ]EdZ,`B4  
boolean bDownOver = false; //Downing is over B_ bZ
a  
boolean bStop = false; //Stop identical wU|jw(  
FileAccessI fileAccessI = null; //File Access interface ic}mru  
L}rYh`bUP[  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException K #}t
\  
{ /h8100  
this.sURL = sURL; r+;k(HMY}[  
this.nStartPos = nStart; h.q9p!  
this.nEndPos = nEnd; Ko0?c.l  
nThreadID = id; p}8?#5`/w  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 3Uej]}c  
} _{$<s[S  
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public void run() a[p$e?gka  
{ 2S-f5&o  
while(nStartPos < nEndPos && !bStop) #_WkV  
{ bj
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try{ 5= T$h;O  
URL url = new URL(sURL); ),Hr  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 3^5h:OaT  
httpConnection.setRequestProperty("User-Agent","NetFox"); Z<,Hz+  
String sProperty = "bytes="+nStartPos+"-"; $PRUzFZ  
httpConnection.setRequestProperty("RANGE",sProperty); _r>kR7A\{  
Utility.log(sProperty); X8):R
- J  
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InputStream input = httpConnection.getInputStream(); ~F%sO'4!  
//logResponseHead(httpConnection); q1v7(`O  
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byte[] b = new byte[1024]; 5p6/dlN-a  
int nRead; H4W!Md  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) '2 Y8  
{ 7M8cF>o  
nStartPos += fileAccessI.write(b,0,nRead); NY|hE@{2.  
//if(nThreadID == 1) >~_z#2PA  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); `@ny!S|1/  
} Kg`P@  
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Utility.log("Thread " + nThreadID + " is over!"); !{fu(E  
bDownOver = true; "!CV
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//nPos = fileAccessI.write (b,0,nRead); @Ne&%F?^Z  
} [5ncBY*A7  
catch(Exception e){e.printStackTrace ();} Kj)sL0  
} 41P0)o  
} s\<UDW  
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//打印回应的头信息 6TTu[*0NT  
public void logResponseHead(HttpURLConnection con) aRElk&M  
{ 8!YQ9T[  
for(int i=1;;i++)  q*94vo-  
{ $41<ldJ  
String header=con.getHeaderFieldKey(i); "?<(-,T  
if(header!=null) /GX
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); &xA>(|a\&-  
Utility.log(header+" : "+con.getHeaderField(header)); vxOnv8(  
else (E7"GJ  
break; &nwS7n1eb  
} pU'${Z~b  
} M?DZShkV_  

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public void splitterStop() ![$`Ivro`  
{ [+QyKyhTO  
bStop = true; P j,H]  
} 8:)[.  
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} (P;TM1k  
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/* \o=9WKc  
**FileAccess.java 5gV,^[E-z  
*//文件访问(定位，写) DB
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package NetFox; LT>_Y`5>  
import java.io.*; hW'b'x<  
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,|A6l?iV  
public class FileAccessI implements Serializable{ ?@Q0;LG  
<T;V9(66  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 *C0a,G4  
RandomAccessFile oSavedFile; 8EMBqhl  
long nPos; 'wtb"0 }  
{&XTa`C  
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public FileAccessI() throws IOException B9[vv;lzu  
{ ~cyKPg6  
this("",0); q'a]D
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} cMF)2^w}  
|d-x2M[  
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public FileAccessI(String sName,long nPos) throws IOException +H?g9v40  
{ VcXr!4M  
oSavedFile = new RandomAccessFile(sName,"rw"); "" >Yw/'  
this.nPos = nPos; 6"Lyv  
oSavedFile.seek(nPos); Q)BSngW+  
} bcjh3WP  
YFPse.2$a  
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public synchronized int write(byte[] b,int nStart,int nLen) G6qZ>-GiL  
{ 8_w6% md  
int n = -1; J%|;  
try{ &WLN   
oSavedFile.write(b,nStart,nLen); R9^vAS4t[O  
n = nLen; H\n6t-l  
} DTuco9yr[  
catch(IOException e) XR9kxTuk  
{ )B+o F7  
e.printStackTrace (); $GU s\  
} ("PZ!z1m1  
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return n; fZr{x$]N0  
} $[ S 33Q  
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} 5%(whSKZF  
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/* xzOvc<u  
**SiteInfoBean.java A'7Y{oPHX  
*/ $H.U ~  
package NetFox; WRkuP
j2  
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public class SiteInfoBean { v;G/8>GRy  
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private String sSiteURL; //Site's URL ^H2TSaJ;  
private String sFilePath; //Saved File's Path X]2Ib'(  
private String sFileName; //Saved File's Name x9\{a  
private int nSplitter; //Count of Splited Downloading File Z:,\FB_U  
\Gk}Fer  
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public SiteInfoBean() c(vi,U-hC  
{//nSplitter的缺省值为5 [h-NX  
//default value of nSplitter is 5 E#Ue9J  
this("","","",5); 1|-C(UW>  
} -c1-vGW/  
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i <gt`UCO  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 04=RoYMM  
{ ^`dMjeF  
sSiteURL= sURL; BR?DW~7J j  
sFilePath = sPath; v(JjvN21  
sFileName = sName; *y|w9rp  
this.nSplitter = nSpiltter;
c)N_"#&  
ZVJ6 {DS/  
"QS(4yw?jg  
} 0Bp0ScE|FA  
7Dl^5q.|  
'Kkp!eZQ~  
public String getSSiteURL() I]5){Q"S  
{ IcQpbF0  
return sSiteURL; s/~pr.>-l  
} .,(x7?  
~2XGw9`J2  
|5FEsts[  
public void setSSiteURL(String value) !,Gavt7f  
{ `FNU- I4s  
sSiteURL = value; 7^Us  
} q[vO mes  
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RT'5i$q
[  
public String getSFilePath() Zn.S65J*u  
{ E=S_1  
return sFilePath; sA: /!9  
} i=>`=. ~  
tRc3<>  
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public void setSFilePath(String value) bOrE86v:  
{ yGWl8\,j0  
sFilePath = value;
s5{H15  
} ^mI`P}5Y  
v6aMYmenBH  
X=6L-^o)  
public String getSFileName() WTt /y\'6  
{ K^GvU0\  
return sFileName; iH]0 YT.E  
} +JD^5J,-NJ  
>2}*L"YC  
_f "I%QTL  
public void setSFileName(String value) :18}$  
{ hZUS#75M5  
sFileName = value; jL4"FTcE]3  
} RN1KM  
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=8p[ (<F=  
public int getNSplitter() jamai
8  
{ }l]r-  
return nSplitter; HP3%CB  
} <>-gQ9  
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public void setNSplitter(int nCount) +U<Ae^V
 
{ S*3$1BTl  
nSplitter = nCount; >B;S;_5=  
} q4"^G:  
} aG@GJ@w  
>/@Q7V99{  
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/* D,-L!P  
**Utility.java ;tD?a7  
*/ EmP2r*"rb  
package NetFox; P:XX8&#  
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flBJO.2  
public class Utility { #^i+'Z=L  
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public Utility() p<@+0Uw2  
{ X/Fip0i  
={190=\9  
;lTgihW-  
} <_bGV  
)In;nc  
//线程睡眠 F>@z&a}(  
public static void sleep(int nSecond) d+eb![fi  
{ mUb2U&6(  
try{ [vdC$9z,  
Thread.sleep(nSecond); =E~SaT  
} <sGioMr  
catch(Exception e) 9x8Ai  
{ | 8n,|%e  
e.printStackTrace (); yAel4b/}  
} 1&kf2\S  
} )=,;-&AR  
6XVJ/q
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//日志 u`*
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public static void log(String sMsg) aMJ9U)wnK  
{ bV@5B#] 2R  
System.err.println(sMsg); 2fUz}w (  
} oX/#Mct{s  
ju"j?2+F  
R ta_\Aj!  
public static void log(int sMsg) 9'p p
b  
{ IifH=%2Y  
System.err.println(sMsg); xU9^8,6  
} _j_c&  
} :Sk<0VVd7  
"r{ ^Y??  
z]i
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/* m%OX< T!  
**TestMethod.java #xrE^Txh  
*/ 1g|6,J  
package NetFox; Rmh,P>  
<,T#* fg  
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public class TestMethod { )#cGePA  
?[O Sy.6  
l{\@+m  
public TestMethod() n8e}8.Bu  
{ ///xx/weblogic60b2_win.exe 3Q+THg3~?  
try{ qSL~A-  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 2 BwpxV8  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); LGVGr  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Tj=g[)+K  
fileFetch.start(); GwlAEhP  
} =j1Q5@vS  
catch(Exception e){e.printStackTrace ();} 3+%L[fW`/  
|G-o&m"  
'P-FeN^  
} RK=YFE 0  
MXpj_+@  
m=IA/HOR^  
public static void main(String[] args) \RTXfe-`  
{ -Ar 3>d  
new TestMethod(); K<Y-/t  
} 7Rom#Kl:  
}  _$4vk  
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